Showing papers in "British Journal of Ophthalmology in 2005"

Limbal epithelial crypts: a novel anatomical structure and a putative limbal stem cell niche

Abstract: Background/aims There is substantial evidence that mammalian epithelial stem cells are located within well defined niches. Although the corneoscleral limbus is acknowledged as the site of corneal epithelial stem cells no anatomical niche for such cells has yet been described. The authors undertook to re-evaluate the microanatomy of the limbus in order to identify possible sites that may represent a stem cell niche. Methods Systematic serial 5-7 microm sections of human corneoscleral segments obtained from cadaver donors, were examined. The sections were stained with haematoxylin and eosin or toludine blue. Sections with specific areas of interest were further examined immunohistologically for the corneal epithelial marker cytokeratin 14 and the "stem cell" marker ABCG2 transporter protein. Results Distinct anatomical extensions from the peripheral aspect of the limbal palisades were identified. These consist of a solid cord of cells extending peripherally or circumferentially. The cells stained positive for CK14 and ABCG2. Conclusions A novel anatomical structure has been identified at the human limbus, which demonstrates characteristics of being a stem cell niche. The authors have termed this structure the limbal epithelial crypt.

Falls and health status in elderly women following first eye cataract surgery: a randomised controlled trial

Abstract: Background/aim: A third of elderly people fall each year Poor vision is associated with increased risk of falls The authors aimed to determine if first eye cataract surgery reduces the risk of falling, and to measure associated health gain Methods: 306 women aged over 70, with cataract, were randomised to expedited (approximately 4 weeks) or routine (12 months wait) surgery Falls were ascertained by diary, with follow up every 3 months Health status was measured after 6 months Results: Visual function improved in the operated group (corrected binocular acuity improved by 025 logMAR units; 8% had acuity worse than 6/12 compared with 37% of controls) Over 12 months of follow up, 76 (49%) operated participants fell at least once, and 28 (18%) fell more than once 69 (45%) unoperated participants fell at least once, 38 (25%) fell more than once Rate of falling was reduced by 34% in the operated group (rate ratio 066, 95% confidence interval 045 to 096, p = 003) Activity, anxiety, depression, confidence, visual disability, and handicap all improved in the operated group compared with the control group Four participants in the operated group had fractures (3%), compared with 12 (8%) in the control group (p = 004) Conclusion: First eye cataract surgery reduces the rate of falling, and risk of fractures and improves visual function and general health status

The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry

Abstract: Aims: To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT). Methods: CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. Results: A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 μm increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p⩽0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects. Conclusion: IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen.

Impact of unilateral and bilateral vision loss on quality of life

Abstract: This is a publisher’s version of an article published in British Journal of Opthalmology 2005 published by BMJ Publishing. http://bjo.bmj.com/

Intraocular pressure and systemic blood pressure: longitudinal perspective: the Beaver Dam Eye Study

Abstract: Aim: To investigate the relation between change in systemic blood pressures and change in intraocular pressure. Methods: This was a population based study of people 43–86 years old living in Beaver Dam, Wisconsin. Measurements at baseline (1988–90) and 5 year follow up of systemic blood pressures, intraocular pressures, and history of use of blood pressure medications. Results: Intraocular pressures were significantly correlated with systolic and diastolic blood pressures at both baseline and follow up. There were significant direct correlations between changes in systemic blood pressures and changes in intraocular pressure. There was a 0.21 (95% CI: 0.16 to 0.27) mm Hg increase in IOP for a 10 mm Hg increase in systolic and 0.43 (0.35 to 0.52) mm Hg increase in IOP for a 10 mm Hg increase in diastolic blood pressure. Further adjustment for diabetes and medication use did not alter these associations. Decreased systolic or diastolic blood pressures of more than 10 mm Hg over 5 years were significantly associated with decreased IOP. Conclusions: Reduced systemic blood pressure is associated with reduced intraocular pressure. This finding should be evaluated in other studies, especially with respect to the possibility of resultant decreased risk of open angle glaucoma.

A randomised, prospective study comparing selective laser trabeculoplasty with latanoprost for the control of intraocular pressure in ocular hypertension and open angle glaucoma

Abstract: Aim: To compare 90°, 180°, and 360° selective laser trabeculoplasty (SLT, 532 nm Nd:YAG laser) with latanoprost 0.005% for the control of intraocular pressure (IOP) in ocular hypertension (OHT) and open angle glaucoma (OAG). Methods: A prospective, randomised clinical trial in the Department of Ophthalmology, St Thomas’s Hospital, London, and Clayton Eye Centre, Wakefield, West Yorkshire. 167 patients (167 eyes) with either OHT or OAG were randomised to receive 90°, 180°, and 360° SLT or latanoprost 0.005% at night and were evaluated at 1 hour, 1 day, 1 week and 1, 3, 6, and 12 months. Results: The mean follow up was 10.3 months (range 1–12 months). Early, transient, complications such as postoperative ocular pain, uveitis, and 1 hour IOP spike occurred in a number of eyes after SLT, with pain being reported more frequently after 360° than 90° treatments (p>0.001). Success rates defined in terms of both a 20% or more and a 30% or more IOP reduction from baseline measurements with no additional antiglaucomatous interventions were better with latanoprost than 90° (p 20% IOP reduction and 59% a >30% reduction from baseline. Although success rates were better with 360° than 180° SLT treatments, differences did not reach statistical significance. There were no differences with regard to age, sex, race, pretreatment IOP, OHT versus OAG, laser power settings, and total laser energy delivered between eyes which responded, in terms of a >20% and a >30% IOP reduction, and those that did not respond with 180° and 360° SLT treatments. Conclusions: Success rates were higher with latanoprost 0.005% at night than with 90° and 180° SLT treatments. 90° SLT is generally not effective. 360° SLT appears to be an effective treatment with approximately 60% of eyes achieving an IOP reduction of 30% or more. Transient anterior uveitis with associated ocular discomfort is not unusual in the first few days after SLT. Late complications causing ocular morbidity after SLT were not encountered.

Incidence of keratitis of varying severity among contact lens wearers

Abstract: Aim: To determine the incidence of non-severe keratitis (NSK) and severe keratitis (SK) among wearers of current generation contact lenses. Methods: A 12 month, prospective, hospital based epidemiological study was conducted by examining all contact lens wearers presenting with a corneal infiltrate/ulcer to a hospital centre in Manchester. A clinical severity matrix was used to differentiate between NSK and SK, based on the severity of signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear (DW) or extended wear (EW)) and lens types being used were estimated from relevant demographic and market data. Results: During the survey period, 80 and 38 patients presented with NSK and SK, respectively. The annual incidences (cases per 10 000 wearers) for each wearing modality and lens type were: DW rigid—NSK 5.7, SK 2.9; DW hydrogel daily disposable—NSK 9.1, SK 4.9; DW hydrogel (excluding daily disposable)—NSK 14.1, SK 6.4; DW silicone hydrogel—NSK 55.9, SK 0.0; EW rigid—NSK 0.0, SK 0.0; EW hydrogel—NSK 48.2, SK 96.4; EW silicone hydrogel—NSK 98.8, SK 19.8. The difference in SK between EW hydrogel and EW silicone hydrogel was significant (p = 0.04). Conclusions: A clinical severity matrix has considerable utility in assessing contact lens related keratitis. There is a significantly higher incidence of SK in wearers who sleep in contact lenses compared with those who only use lenses during the waking hours. Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of SK for extended wear compared with hydrogel lenses.

Subthreshold diode micropulse photocoagulation for the treatment of clinically significant diabetic macular oedema.

Abstract: Aim: To report the visual and clinical outcomes of a pilot study of subthreshold diode micropulse (SDM) laser photocoagulation for clinically significant diabetic macular oedema (CSMO). Methods: The results of infrared (810 nm) SDM laser photocoagulation for CSMO were retrospectively reviewed in 95 eyes of 69 consecutive patients with mild to moderate non-proliferative diabetic retinopathy. The same laser parameters were used for each patient. Only the number of laser applications varied between patients, depending on their macular findings. Primary outcome measures were Snellen visual acuity, fluorescein angiographic leakage, and CSMO status. Results: Visual acuity was stable or improved in 85% of treated eyes, with a mean follow up of 12.2 months (range 3–29 months). CSMO decreased in 96% and resolved in 79% of treated eyes. No adverse laser events occurred. No laser lesions were detectable ophthalmoscopically or angiographically after treatment, consistent with calculations based on ANSI Z136.1 laser safety standards suggestive of only histologically detectable tissue effects at the laser exposure levels. No laser scarring was observed during the follow up period. Conclusion: Subthreshold diode micropulse laser photocoagulation minimises chorioretinal damage in the management of CSMO and demonstrates a beneficial effect on visual acuity and CSMO resolution. Prospective studies are needed to fully evaluate this technique.

Direct costs of glaucoma and severity of the disease: a multinational long term study of resource utilisation in Europe

Abstract: Background: Resource utilisation and direct costs associated with glaucoma progression in Europe are unknown. As population progressively ages, the economic impact of the disease will increase. Methods: From a total of 1655 consecutive cases, the records of 194 patients were selected and stratified by disease severity. Record selection was based on diagnoses of primary open angle glaucoma, glaucoma suspect, ocular hypertension, or normal tension glaucoma; 5 years minimum follow up were required. Glaucoma severity was assessed using a six stage glaucoma staging system based on static threshold visual field parameters. Resource utilisation data were abstracted from the charts and unit costs were applied to estimate direct costs to the payer. Resource utilisation and estimated direct cost of treatment, per person year, were calculated. Results: A statistically significant increasing linear trend (p = 0.018) in direct cost as disease severity worsened was demonstrated. The direct cost of treatment increased by an estimated €86 for each incremental step ranging from €455 per person year for stage 0 to €969 per person year for stage 4 disease. Medication costs ranged from 42% to 56% of total direct cost for all stages of disease. Conclusions: These results demonstrate for the first time in Europe that resource utilisation and direct medical costs of glaucoma management increase with worsening disease severity. Based on these findings, managing glaucoma and effectively delaying disease progression would be expected to significantly reduce the economic burden of this disease. These data are relevant to general practitioners and healthcare administrators who have a direct influence on the distribution of resources.

A comparison of four methods of tonometry: method agreement and interobserver variability.

Abstract: Aim: To compare the inter-method agreement in intraocular pressure (IOP) measurements made with four different tonometric methods. Methods: IOP was measured with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT) in a randomised order in one eye of each of 105 patients with ocular hypertension or glaucoma. Three measurements were made with each method, and by each of two independent GAT observers. GAT interobserver and tonometer inter-method agreement was assessed by the Bland-Altman method. The outcome measures were 95% limits of agreement for IOP measurements between GAT observers and between tonometric methods, and 95% confidence intervals for intra-session repeated measurements. Results: The mean differences (bias) in IOP measurements were 0.4 mm Hg between GAT observers, and 0.6 mm Hg, 0.1 mm Hg, and 0.7 mm Hg between GAT and Tono-Pen, OBF, and NCT, respectively. The 95% limits of agreement were smallest (bias ±2.6 mm Hg) between GAT observers, and larger for agreement between the GAT and the Tono-Pen, OBF, and NCT (bias ±6.7, ±5.5, and ±4.8 mm Hg, respectively). The OBF and NCT significantly underestimated GAT measurements at lower IOP and overestimated these at higher IOP. The repeatability coefficients for intra-session repeated measurement for each method were ±2.2 mm Hg and ±2.5 mm Hg for the GAT, ±4.3 mm Hg for the Tono-Pen, ±3.7 mm Hg for the OBF, and ±3.2 mm Hg for the NCT. Conclusions: There was good interobserver agreement with the GAT and moderate agreement between the NCT and GAT. The differences between the GAT and OBF and between the GAT and Tono-Pen probably preclude the OBF and Tono-Pen from routine clinical use as objective methods to measure IOP in normal adult eyes.

Current estimates of blindness in India

Abstract: Background: Evidence based planning has been the hallmark of the blindness control programme in India. A nationwide survey was undertaken in 1999–2001 to document the magnitude and causes of blindness. Methods: One district each in 15 populous states was covered. 25 clusters were randomly selected in each district and all individuals aged 50 years and above were enumerated. Presenting and best corrected vision was recorded using retroilluminated logMAR tumbling E charts and detailed eye examination was offered. Results: The response rate was 89.3%. Presenting vision Conclusion: Blindness control efforts seem to have played a part in arresting the increasing prevalence of blindness in India and there is hope that the goals of the “Vision 2020—right to sight” initiative can be achieved if there is strong political will and prioritised action.

Correlation between retinal nerve fibre layer thickness and optic nerve head size: an optical coherence tomography study

Abstract: Aim: To investigate the correlation between retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) size in normal white subjects by means of optical coherence tomography (OCT). Methods: 54 eyes of 54 healthy subjects aged between 15 and 54 underwent peripapillary RNFL thickness measurement by a series of three circular scans with a 3.4 mm diameter (Stratus OCT, RNFL Thickness 3.4 acquisition protocol). ONH analysis was performed by means of six radial scans centred on the optic disc (Stratus OCT, Fast Optic Disc acquisition protocol). The mean RNFL values were correlated with the data obtained by ONH analysis. Results: The superior, nasal, and inferior quadrant RNFL thickness showed a significant correlation with the optic disc area (R = 0.3822, p = 0.0043), (R = 0.3024, p = 0.026), (R = 0.4048, p = 0.0024) and the horizontal disc diameter (R = 0.2971, p = 0.0291), (R = 0.2752, p = 0.044), (R = 0.3970, p = 0.003). The superior and inferior quadrant RNFL thickness was also positively correlated with the vertical disc diameter (R = 0.3774, p = 0.0049), (R = 0.2793, p = 0.0408). A significant correlation was observed between the 360° average RNFL thickness and the optic disc area and the vertical and horizontal disc diameters of the ONH (R = 0.4985, p = 0.0001), (R = 0.4454, p = 0.0007), (R = 0.4301, p = 0.0012). Conclusions: RNFL thickness measurements obtained by Stratus OCT increased significantly with an increase in optic disc size. It is not clear if eyes with large ONHs show a thicker RNFL as a result of an increased amount of nerve fibres or to the shorter distance between the circular scan and the optic disc edge.

Enhanced optical coherence tomography imaging by multiple scan averaging.

Abstract: Aims: To describe a method for computerised alignment and averaging of sequences in optical coherence tomography (OCT) B-scans and to present selected clinical observations based on the resulting improvement in retinal imaging. Methods: A methodological study and retrospective investigation of selected cases. Five human subjects were included, one healthy subject, two patients with central serous chorioretinopathy, one patient with branch retinal vein occlusion, and one patient with cilioretinal artery pseudo-occlusion. Based on computerised alignment of sets of B-scans obtained at identical retinal locations, average OCT images were produced and displayed in false colour or grayscale. These enhanced tomograms were compared with other morphological and functional characteristics. Results: Improved retinal imaging enabled assignment of the OCT image to retinal anatomy particularly at the outer layer of the photoreceptors and the retinal pigment epithelium, both in the healthy eye and in pathology. Identification of both post-oedematous structural disorganisation as well as post-ischaemic attenuation of the inner retina was superior to standard OCT images. Conclusions: Averaging of multiple OCT B-scans enhances the quality of retinal imaging sufficiently to reveal new details of retinal pathophysiology. Using the technique on OCT3 scans enables visualisation of details comparable with the results obtained using ultra high resolution OCT.

Impression cytology of the ocular surface.

Abstract: Impression cytology refers to the application of a cellulose acetate filter to the ocular surface to remove the superficial layers of the ocular surface epithelium. These cells can then be subjected to histological, immunohistological, or molecular analysis. Proper technique is essential as the number of cells sampled can vary considerably. Generally two to three layers of cells are removed in one application but deeper cells can be accessed by repeat application over the same site. Applications for impression cytology include diagnosing a wide range of ocular surface disorders, documenting sequential changes in the conjunctival and corneal surface over time, staging conjunctival squamous metaplasia, and monitoring effects of treatment. It is also a useful investigational tool for analysing ocular surface disease with immunostaining and DNA analysis. It is non-invasive, relatively easy to perform, and yields reliable information about the area sampled with minimal discomfort to the patient. Major ophthalmic centres should develop and introduce this technique into routine clinical practice. This is best achieved with a team approach including the ophthalmologist, pathologist, microbiologist, and the immunologist.

Anti-TNF-alpha therapy for sight threatening uveitis.

Abstract: Aim: To describe the effect of additional treatment with anti-TNF-α therapy in a case series of 13 patients with serious sight threatening uveitis. Methods: 13 patients with serious sight threatening uveitis were included, of whom six had Behcet’s disease, five had idiopathic posterior uveitis, one had sarcoidosis, and one birdshot retinochoroiditis. Onset and course of ocular inflammation, inflammatory signs, and visual acuity were assessed. Patients were treated with 200 mg (approximately 3 mg/kg) infliximab infusion. Repeat infusions were given based on clinical response. Results: Infliximab treatment resulted in an effective suppression of ocular inflammation in all patients. In patients with non-Behcet’s disease uveitis visual acuity in six out of eight improved or was stable. In patients with Behcet’s disease visual acuity in five out of six improved or was stable. Conclusion: Anti-TNF-α treatment may be of value in the treatment of uveitis, and in patients with Behcet’s disease, leading to suppression of ocular inflammation, vasculitis, and improvement of vision in the majority. Based on these results a controlled masked study is warranted.

Endophthalmitis associated with the Ahmed glaucoma valve implant.

Abstract: Aim: To investigate the rate, risk factors, clinical course, and treatment outcomes of endophthalmitis following glaucoma drainage implant (GDI) surgery. Methods: A computerised relational database search was conducted to identify all patients who were implanted with Ahmed glaucoma valve (AGV) and developed endophthalmitis following surgery at the King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia, between 1 January 1994 and 30 November 2003. Only medical records of the patients who developed endophthalmitis were retrospectively reviewed. Results: 542 eyes of 505 patients who were on active follow up were included in the study. Endophthalmitis developed in nine (1.7%) eyes; the rate was five times higher in children than in adults. Delayed endophthalmitis (developed 6 weeks after surgery) occurred in eight of nine eyes. Conjunctival erosion overlying the AGV tube was present in six of nine eyes. Common organisms isolated in the vitreous included Haemophilus influenzae and Streptococcus species. Multiple regression analysis revealed that younger age and conjunctival erosion over the tube were significant risk factors associated with endophthalmitis. Conclusion: Endophthalmitis is a rare complication of GDI surgery that appears to be more common in children. Conjunctival dehiscence over the GDI tube seems to represent a major risk factor for endophthalmitis. Prompt surgical revision of an exposed GDI tube is highly recommended.

The origins of polypoidal choroidal vasculopathy

Abstract: Background/aim: There are two theories on the pathogenesis of polypoidal choroidal vasculopathy (PCV): variants in choroidal neovascularisation (CNV) and inner choroidal vessel abnormalities. On indocyanine green angiography (IGA) with a video camera system, PCV has a characteristic appearance, but inadequate image quality has made detailed interpretation difficult. This study aims to improve imaging, using confocal scanning laser ophthalmoscopy (SLO), to elucidate the pathogenesis of PCV. Methods: High speed IGA with confocal SLO of 45 eyes (44 patients) showed typical PCV findings of a branching vascular network and polypoidal lesions. Results: Vessels comprising branching networks began to fill simultaneously with the surrounding choroidal arteries in 38 eyes. Small numbers of vessels filling within a branching network, in the arterial and arteriovenous phases of IGA, showed focal dilatation, constriction, and tortuousity. Vessel abnormalities, corresponding to polypoidal lesions, existed within a network in eight eyes and included loops similar in calibre to network vessels, and numerous microaneurysmal dilatations of small vessels. Vessel pulsation was seen in 24 eyes. Conclusion: PCV is caused by inner choroidal vessel abnormalities, not CNV.

In vitro and in vivo killing of ocular Demodex by tea tree oil.

Abstract: Aims: To compare the in vitro killing effect of different agents on Demodex and to report the in vivo killing effect of tea tree oil (TTO) on ocular Demodex. Methods: Survival time of Demodex was measured under the microscope. Sampling and counting of Demodex was performed by a modified method. Results: Demodex folliculorum survived for more than 150 minutes in 10% povidone-iodine, 75% alcohol, 50% baby shampoo, and 4% pilocarpine. However, the survival time was significantly shortened to within 15 minutes in 100% alcohol, 100% TTO, 100% caraway oil, or 100% dill weed oil. TTO’s in vitro killing effect was dose dependent. Lid scrub with 50% TTO, but not with 50% baby shampoo, can further stimulate Demodex to move out to the skin. The Demodex count did not reach zero in any of the seven patients receiving daily lid scrub with baby shampoo for 40–350 days. In contrast, the Demodex count dropped to zero in seven of nine patients receiving TTO scrub in 4 weeks without recurrence. Conclusions: Demodex is resistant to a wide range of antiseptic solutions. Weekly lid scrub with 50% TTO and daily lid scrub with tea tree shampoo is effective in eradicating ocular Demodex.

Does visual restitution training change absolute homonymous visual field defects? A fundus controlled study.

Abstract: Aim: To examine whether visual restitution training (VRT) is able to change absolute homonymous field defect, assessed with fundus controlled microperimetry, in patients with hemianopia. Methods: 17 patients with stable homonymous visual field defects before and after a 6 month VRT period were investigated with a specialised microperimetric method using a scanning laser ophthalmoscope (SLO). Fixation was controlled by SLO fundus monitoring. The size of the field defect was quantified by calculating the ratio of the number of absolute defects and the number of test points; the training effect E was defined as the difference between these two ratios before and after training. A shift of the entire vertical visual field border by 1° would result in an E value of 0.14. Results: The mean training effect of all right eyes was E = 0.025 (SD 0.052) and all left eyes E = 0.008 (SD 0.034). In one eye, a slight non-homonymous improvement along the horizontal meridian occurred. Conclusions: In one patient, a slight improvement along the horizontal meridian was found in one eye. In none of the patients was an explicit homonymous change of the absolute field defect border observed after training.

The relative effects of corneal thickness and age on Goldmann applanation tonometry and dynamic contour tonometry.

Abstract: AIMS: To establish the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measured with a prototype Pascal dynamic contour tonometer (DCT), to evaluate the effect of CCT and age on the agreement between IOP measured with the Pascal DCT and Goldmann applanation tonometer (GAT), and to compare the interobserver and intraobserver variation of the DCT with the GAT. METHODS: GAT and DCT IOP measurements were made on 130 eyes of 130 patients and agreement was assessed by means of Bland-Altman plots. The effect of CCT and age on GAT/DCT IOP differences was assessed by linear regression analysis. Interobserver and intraobserver variations for GAT and DCT were assessed in 100 eyes of 100 patients. RESULTS: The mean difference (95% limits of agreement) between GAT and DCT was -0.7 (-6.3 to 4.9) mm Hg. GAT/DCT IOP differences increased with thicker CCT (slope 0.017 mm Hg/microm, 95% CI 0.004 to 0.03, r2 = 0.05, p = 0.01), and with greater age, slope 0.05 mm Hg/year (95% CI 0.012 to 0.084, r2 = 0.05, p = 0.01). The intraobserver variability of GAT and DCT was 1.7 mm Hg and 3.2 mm Hg, respectively. The interobserver variability was (mean difference (95% limits of agreement)) 0.4 (-3.5 to 4.2) mm Hg for GAT and 0.2 (-4.9 to 5.3) mm Hg for DCT. CONCLUSIONS: GAT is significantly more affected than DCT by both CCT and subject age. The effect of age suggests an age related corneal biomechanical change that may induce measurement error additional to that of CCT. The prototype DCT has greater measurement variability than the GAT.

Spare the rod and spoil the eye

Abstract: This review presents a new unified view of the pathogenesis of three common causes of acquired retinal degenerative disease—diabetic retinopathy, age related macular degeneration, and retinopathy of prematurity. In these three conditions, angiogenesis has a predominant role in the development of sight threatening pathology. Angiogenesis is controlled by among other factors the expression of vascular endothelial growth factor (VEGF), which in turn is regulated by absolute and relative lack of oxygen. The severe pathological manifestations of these three conditions are not part of a general underlying disease process because they are peculiar to the eye, and the profound hypoxia that develops in normal retina during dark adaptation (rod driven hypoxia) is an adequate and elegant additional factor to explain their pathogenesis. A large number of experimental reports support this conclusion, although rod driven anoxia is not generally considered as a causal factor in ocular disease. However, the hypothesis can be critically tested, and also suggests novel methods of treatment and prevention of these conditions that may be simpler and more inexpensive than current therapies and that have a smaller potential for adverse effects.

Correlation between surgical success rate and severity of congenital glaucoma

Abstract: Aim: To study the correlation between severity of primary congenital glaucoma (PCG) and success of three types of surgery Methods: This was a retrospective review of all records of patients diagnosed with PCG up to age 1 year who underwent goniotomy, trabeculotomy, or combined trabeculotomy-trabeculectomy with mitomycin C as initial procedure between 1982 and 2002 at the King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia 532 paediatric glaucoma patients below age 1 year (820 eyes) with a minimum 1 year follow up were identified The main outcome measures used for the surgeries were postoperative intraocular pressure, stability of the corneal diameter, and maintenance of corneal clarity Surgical success was defined as a postoperative intraocular pressure of ⩽21 mm Hg without additional medical or surgical therapy, and with decreased corneal oedema, stabilised corneal diameter, and no additional optic nerve damage for at least 1 year after surgery Complications, time of surgical failure, and follow up were recorded Results: The eyes were grouped into mild (249), moderate (342), and severe (229) PCG, based on intraocular pressure, corneal diameter, and clarity All three surgical procedures resulted in high success rates of 81–100% for the mild form of PCG Eyes classified with moderate glaucoma had a 13%, 40%, and 80% success rate respectively for goniotomy, trabeculotomy, and combined trabeculotomy-trabeculectomy with mitomycin C The success rate for severe PCG was 10% and 70% for trabeculotomy and combined surgery respectively Goniotomy was never done for eyes with this condition Conclusion: Clinical classification of PCG is helpful for surgical decision making The mild form has a high surgical success regardless of the procedure chosen Combined trabeculotomy-trabeculectomy with mitomycin C gave the best results for moderate and severe cases of PCG

Incidence and severity of keratoconus in Asir province, Saudi Arabia.

Abstract: Aim: To assess the incidence and associated signs and symptoms of patients with keratoconus in Asir Province, Saudi Arabia. Methods: 125 new keratoconus patients (51 male, 74 female; mean age 18.5 (SD 3.8) years; range 8–28 years) were recruited from referrals to the department of ophthalmology, Asir Central Hospital, over a 1 year period. Age, visual acuity, and keratometry were recorded along with clinical signs and symptoms. Results: The incidence of keratoconus in Asir Province is 20 cases per 100 000 population. Also, the disease severity is high, as indicated by an early mean age (17.7 (3.6) years) with advanced stage keratoconus. Visual acuity, with either spectacles or rigid contact lenses, was 6/12 or better in 98% of eyes measured. Just over half (56%) of patients had atopic ocular disease. 16% of patients had a positive family history of the disease and 16% had atopic dermatitis (eczema and/or vitiligo). Conclusion: The incidence and severity of keratoconus in Asir Province, Saudi Arabia, is high with an early onset and more rapid progress to the severe disease stage at a young age. This might reflect the influence of genetic and/or environmental factor(s) in the aetiology of keratoconus.

Baseline IOP predicts selective laser trabeculoplasty success at 1 year post-treatment: results from a randomised clinical trial

Abstract: Background/aims: The efficacy and safety of selective laser trabeculoplasty (SLT) has been found to be equivalent to argon laser trabeculoplasty (ALT). Since SLT produces significantly less disturbance to the trabecular meshwork and is theoretically more repeatable than ALT, it has potential to replace ALT as the standard procedure to treat medically uncontrolled open angle glaucoma. This study’s objective is to determine factors that predict successful SLT at 1 year post-treatment. Methods: As part of a randomised clinical trial comparing the efficacy and safety of SLT to ALT, data on 72 SLT patients were collected, and successful SLT defined as having an SLT induced intraocular pressure (IOP) reduction of ⩾20% at 1 year post-treatment follow up. Results: 43 out of the 72 patients who had completed their 1 year follow up visit had an IOP reduction of ⩾20% from baseline. No glaucoma risk factors studied predicted successful SLT. The amount of trabecular meshwork pigmentation was not a significant predictor. However, it was discovered that baseline IOP strongly predicted SLT success (odds ratio = 1.16; p = 0.0001). Conclusion: SLT success was significantly predicted by baseline IOP but not by age, sex, other glaucoma risk factors, type of open angle glaucoma, or by degree of trabecular meshwork pigmentation.

Classification of abnormal fundus autofluorescence patterns in the junctional zone of geographic atrophy in patients with age related macular degeneration

Abstract: Aim: To describe and classify patterns of abnormal fundus autofluorescence (FAF) in the junctional zone of geographic atrophy (GA) in patients with age related macular degeneration. Methods: Digital FAF images were recorded in 164 eyes of 107 patients using a confocal scanning laser ophthalmoscope (cSLO; excitation 488 nm, detection above 500 nm) as part of a prospective multicentre natural history study (FAM Study). FAF images were obtained in accordance with a standardised protocol for digital image acquisition and generation of mean images after automated alignment. Results: Image quality was sufficient for classification of FAF patterns in 149 eyes (90.9%) with lens opacities being the most common reason for insufficient image quality. Abnormal FAF outside GA in 149 eyes was classified into four patterns: focal (12.1%), banded (12.8%), patchy (2.0%), and diffuse (57.0%), whereby 12.1% had normal background FAF in the junctional zone. In 4% there was no predominant pattern. The diffuse pattern was subdivided into four groups including reticular (4.7%), branching (27.5%), fine granular (18.1%), and fine granular with peripheral punctate spots (6.7%). Conclusions: Different phenotypic patterns of abnormal FAF in the junctional zone of GA can be identified with cSLO FAF imaging. These distinct patterns may reflect heterogeneity at a cellular and molecular level in contrast with a non-specific ageing process. A refined phenotypic classification may be helpful to identify prognostic determinants for the spread of atrophy and visual loss, for identification of genetic risk factors as well as for the design of future interventional trials.

Bevacizumab suppresses choroidal neovascularisation caused by pathological myopia

Abstract: Bevacizumab (Avastin, Genentech) is a recombinant humanised, full length, anti-VEGF monoclonal antibody that binds all isoforms of VEGF-A. It has been shown to prolong survival of patients with advanced colon cancer when combined with 5-fluorouracil.1 In this report, we describe the effect of bevacizumab in two patients with choroidal neovascularisation (CNV) secondary to pathological myopia, which was refractory to other treatment. ### Patient 1 AM is a 36 year old white man who was diagnosed with subfoveal CNV caused by pathological myopia (right eye = −11.50 D, left eye = −11.50 D) in his left eye in September 2002 for which he received three photodynamic therapy (PDT) treatments. He developed subfoveal CNV in his right eye in June 2003 and received one PDT treatment combined with an intravitreous injection of 4 mg of triamcinolone acetonide. In May 2004, he presented with recurrent subfoveal CNV in his right eye and refused PDT. Off-label use of bevacizumab was discussed and after informed consent, the patient decided to proceed. Just before treatment in July 2004, best corrected visual acuity (VA) was 20/40 in the right eye and 20/25 in the left eye. There was a ring of hyperpigmentation centred on the fovea with a surrounding ring of subretinal blood and substantial subretinal fluid in the right eye (fig 1A). An optical coherence tomography (OCT) scan through the centre of the fovea confirmed the presence of extensive subretinal fluid (fig 1B, asterisks) with subretinal tissue in the centre of the fovea (arrowheads). An OCT map showed severe thickening and subretinal fluid throughout the centre of the macula (foveal thickness 510 μm, macular volume 9.29 mm3). In the left eye, there were pigmentary changes and no subretinal blood or fluid (foveal thickness, 201 μm). In the right eye, the early phase of a fluorescein angiography (FA) …

Outcomes of high volume cataract surgeries in a developing country

Abstract: Aim: To analyse the outcome of high volume cataract surgery in a developing country, community based, high volume eye hospital. Methods: In a non-comparative interventional case series, the authors reviewed the surgical outcomes of 593 patients with cataract operated upon by three high volume surgeons on six randomly selected days. There were 318 female (54%) and 275 male (46%) patients. Their mean age was 59.57 (SD 10.13) years. The majority of the patients underwent manual small incision cataract surgery (manual SICS). Extracapsular cataract extraction with posterior chamber intraocular lens (ECCE-PCIOL) and intracapsular cataract extraction (ICCE) were also done on a few patients as clinically indicated. Results: Best corrected visual acuity of ⩾6/18 was achieved in 94% of the 520 patients who could be followed up on the 40th postoperative day (88% follow up rate). Intraoperative and immediate postoperative complications as defined by OCTET occurred in 11 (1.9%) and 75 (12.6%) patients, respectively. Average surgical time of 3.75 minutes per case (16–18 cases per hour) was achieved. Statistically significant risk factors for outcomes were found to be age >60, sex, and surgeon. Conclusion: High volume surgery using appropriate techniques and standardised protocols does not compromise quality of outcomes.

A new insight into the cellular regulation of aqueous outflow: how trabecular meshwork endothelial cells drive a mechanism that regulates the permeability of Schlemm’s canal endothelial cells

Abstract: Aim: To test the hypothesis that trabecular meshwork endothelial cells (TMEs) increase the permeability of Schlemm’s canal endothelial cells (SCEs) by actively releasing ligands that modulate the barrier properties of SCEs. Methods: The TMEs were first irradiated with a laser light and allowed to condition the medium, which is then added to SCEs. The treatment response is determined by both measuring SCE permeability (flow meters) and the differential expression of genes (Affymetrix chips and quantitative polymerase chain reaction (PCR)). The cytokines secreted by the treated cells were identified using ELISA and the ability of these cytokines to increase permeability is tested directly after their addition to SCEs in perfusion experiments. Results: SCEs exposed to medium conditioned by the light activated TMEs (TME-cm) respond by undergoing a differential expression (DE) of 1120 genes relative to controls. This response is intense relative to a DE of only 12 genes in lasered SCEs. The TME-cm treatment of SCEs increased the SCE permeability fourfold. The role of cytokines in these responses is supported by two findings: adding specific cytokines established to be secreted by lasered TMEs to SCEs increases permeability; and inactivating the TME-cm by boiling or diluting, abrogates these conditioned media permeability effects. Conclusion: These experiments show that TMEs can regulate SCE permeability and that it is likely that TMEs have a major role in the regulation of aqueous outflow. This novel TME driven cellular mechanism has important implications for the pathogenesis of glaucoma and the mechanism of action of laser trabeculoplasty. Ligands identified as regulating SCE permeability have potential use for glaucoma therapy.

Orbital exenteration: a 13 year Manchester experience

Abstract: Background/aims: Orbital exenteration is a psychologically and anatomically disfiguring procedure reserved for the treatment of potentially life threatening malignancies or relentlessly progressive conditions unresponsive to other treatments. In this study the authors aimed to review their experience with exenteration, including indications, outcomes, and reasons for the increased rate of exenterations over the past 15 months. Method: This retrospective study reviewed operating department records via a computerised database to identify all patients who had undergone exenteration of the orbit from 1 January 1991 to 1 April 2004 inclusive, at the Manchester Royal Eye Hospital. Where case records were unavailable, attempts were made to obtain patient data from general practitioners, local health authorities, and referring hospitals. Results: 69 orbits of 68 patients were identified. The mean age of the cohort was 68.2 years, with 33 males and 35 females having undergone exenterations. In total, 31 patients had previously undergone treatments undertaken by the referring specialty with a mean time from the primary procedure to exenteration of 115 months. 14 different tumours were encountered, of which basal cell carcinoma (28), melanoma (10), sebaceous cell carcinoma (nine), and squamous cell carcinoma (six) were the most common. An increasing incidence was observed in cases of BCCs requiring exenteration. 30 patients received orbital prosthesis within an 11 month period post-exenteration. Conclusion: Exenteration is a procedure performed with increasing frequency in this unit over the past 15 months, the majority the result of BCCs. A large proportion of these exenterations had undergone previous treatments under a variety of non-ophthalmic specialties in other units. Exenterations are disfiguring procedures that may, therefore, be reduced in incidence by aggressive removal at the time of primary removal. Once performed, the cosmetic rehabilitation is long, with multiple postoperative visits, independent of the method used to close the orbital defect.

Uveitis in children and adolescents.

Abstract: Aims: To study the relative occurrence of uveitis (intraocular inflammation) and its causes in children and adolescents. Methods: Patients with uveitis examined and followed during a period of 10 years were categorised by age and sex. All underwent ocular examination and an individually tailored battery of laboratory tests. The intraocular manifestations were classified according to the anatomical location of the inflammation and their most probable cause. The final diagnosis was based on typical clinical ocular and extraocular symptoms and signs and on the results of specific laboratory investigations. Results: Out of 821 patients, 276 (33.1%) were 18 years of age or younger with a male to female ratio of 1 to 1. In these 276 children and adolescents, 70.3% had bilateral ocular involvement. Intermediate uveitis was the most frequent anatomical diagnosis. In many cases, symptoms were mild despite the prominent signs and marked decrease of vision. The underlying cause for the uveitis was evaluated as non-infectious in 184 cases (66.7%) and infectious in 92 cases (33.3%). A potential aetiology and/or a definite clinical diagnosis were established in 74.6% of the cases and only 25.4% of the 276 patients were classified as idiopathic. Juvenile idiopathic arthritis (JIA) was the most common systemic disease association diagnosed in 14.9% of these children. Parasite infestation was the most common infectious association. Conclusions: Uveitis in children and adolescents is not as low as previously reported. Parasite infestation on the one hand and JIA on the other hand are the most common aetiologies associated with the uveitis in these young patients.