Clinics in Developmental Medicine

OBJECTIVE:
Retinopathy of prematurity (ROP) is a potentially avoidable cause of blindness in children. The proportion of blindness as a result of ROP varies greatly among countries depending on their level of development, being influenced by the availability of neonatal care, neonatal outcomes, and whether effective screening and treatment programs are in place. The objective of this study was to compare characteristics of premature infants who developed severe ROP between 1996 and 2002 in highly developed countries with less developed countries.
METHODS:
This was an observational study. A questionnaire was completed by ophthalmologists in countries with low, moderate, and high development rankings (3 highly developed countries and from 10 less well-developed countries) who screen for ROP in which they supplied birth weights and gestational ages (GAs) of infants who were treated for threshold ROP or identified with more advanced stages of the disease. Birth weights and GAs of infants with severe ROP were measured.
RESULTS:
The mean birth weights of infants from highly developed countries ranged from 737 to 763 g compared with values ranging from 903 to 1527 g in less developed countries. Mean GAs of infants from highly developed countries ranged from 25.3 to 25.6 weeks compared with 26.3 to 33.5 weeks in less developed countries. A total of 13.0% of 1091 infants from poorly developed countries exceeded United Kingdom screening criteria; 3.6% exceeded a criteria of <34 weeks' GA and/or <1750 g birth weight.
CONCLUSIONS:
These findings suggest that larger, more mature infants are developing severe ROP in countries with low/moderate levels of development compared with highly developed countries. ROP screening programs need to use criteria that are appropriate for their local population.

http://pediatrics.aappublications.org/content/pediatrics/115/5/e518.full.pdf

Characteristics of Infants With Severe Retinopathy of Prematurity in Countries With Low, Moderate, and High Levels of Development: Implications for Screening Programs

The inflammatory process of the uvea is called uveitis and may cause sight threatening damage to the eye. The aetiological factor in about 30% of the cases of uveitis is unknown. If established clinical entities without known cause, such as Fuchs' uveitis, are included, no aetiological agent or association with systemic disease can be identified in about 50% of cases.' Uveitis may be induced by infection, autoimmune disease, trauma, or malignancy. It is recommended that the different forms of uveitis should be classified according to their anatomical localisationanterior uveitis, intermediate uveitis, posterior uveitis, and panuveitis."3 The uvea plays an important role in the ocular immunological defence mechanisms. Immunologically speaking the eye has a deviant and privileged position because of the blood-retina barrier, absence of lymphatic drainage, and a special feature called the anterior chamber associated immune deviation (ACAID). These special defence mechanisms contribute to the preservation of vision.4 If these defence mechanisms fail, intraocular inflammation

https://bjo.bmj.com/content/bjophthalmol/80/9/844.full.pdf

The possible impact of uveitis in blindness: a literature survey.

Retinopathy of prematurity (ROP) is a common blinding disease in children in the developed world despite current treatment, and is becoming increasingly prevalent in the developing world. ROP progresses in two phases. The first phase begins with delayed retinal vascular growth after birth and partial regression of existing vessels, followed by a second phase of hypoxia-induced pathological vessel growth. Two major risk factors of ROP are the use of oxygen and a decreased gestation period. Excessive oxygen contributes to ROP through regulation of vascular endothelial growth factor (VEGF). Suppression of VEGF by oxygen in phase I of ROP inhibits normal vessel growth, whereas elevated levels of VEGF induced by hypoxia in phase II of ROP precipitate pathological vessel proliferation. Insulin-like growth factor 1 (IGF-1) is a critical non-oxygen-regulated factor in ROP. We have found that serum levels of IGF-1 in premature babies directly correlate with the severity of clinical ROP. IGF-1 acts indirectly as a permissive factor by allowing maximal VEGF stimulation of vessel growth. Lack of IGF-1 in preterm infants prevents normal retinal vascular growth in phase I of ROP, despite the presence of VEGF. As infants mature, rising levels of IGF-1 in phase II of ROP allows VEGF stimulated pathological neovascularization. These findings suggest that restoration of IGF-1 to normal levels might be useful in preventing ROP in preterm infants.

/pdf/retinopathy-of-prematurity-3a0x9e69fz.pdf

Retinopathy of Prematurity

Objectives To report on the causes of blindness certifications in England and Wales in working age adults (16–64 years) in 2009–2010; and to compare these with figures from 1999 to 2000. Design Analysis of the national database of blindness certificates of vision impairment (CVIs) received by the Certifications Office. Setting and participants Working age (16–64 years) population of England and Wales. Main outcome measures Number and cause of blindness certifications. Results The Certifications Office received 1756 CVIs for blindness from persons aged between 16 and 64 inclusive between 1 April 2009 and 31 March 2010. The main causes of blindness certifications were hereditary retinal disorders (354 certifications comprising 20.2% of the total), diabetic retinopathy/maculopathy (253 persons, 14.4%) and optic atrophy (248 persons, 14.1%). Together, these three leading causes accounted for almost 50% of all blindness certifications. Between 1 April 1999 and 31 March 2000, the leading causes of blindness certification were diabetic retinopathy/maculopathy (17.7%), hereditary retinal disorders (15.8%) and optic atrophy (10.1%). Conclusions For the first time in at least five decades, diabetic retinopathy/maculopathy is no longer the leading cause of certifiable blindness among working age adults in England and Wales, having been overtaken by inherited retinal disorders. This change may be related to factors including the introduction of nationwide diabetic retinopathy screening programmes in England and Wales and improved glycaemic control. Inherited retinal disease, now representing the commonest cause of certification in the working age population, has clinical and research implications, including with respect to the provision of care/resources in the NHS and the allocation of research funding.

https://bmjopen.bmj.com/content/bmjopen/4/2/e004015.full.pdf

A comparison of the causes of blindness certifications in England and Wales in working age adults (16–64 years), 1999–2000 with 2009–2010

METHODS. The study comprised three distinct phases: baseline, in which repeat measures of visual function were undertaken to confirm the initial visual deficit; refractive adaptation: an 18-week period of spectacle wear with six weekly measurements of logarithm of the minimum angle of resolution (logMAR) visual acuity; occlusion: in which participants were prescribed 6 hours of “patching” per day. In the latter phase, occlusion was objectively monitored and logMAR visual acuity recorded at 2-week intervals until any observed gains had ceased. RESULTS. Data were obtained from 94 participants (mean age, 5.1 1.4 years) with amblyopia associated with strabismus (n 34), anisometropia (n 23), and both anisometropia and strabismus (n 37). Eighty-six underwent refractive adaptation. Average concordance with patching was 48%. The relationship between logMAR visual acuity gain and total occlusion dose was monotonic and linear. Increasing dose rate beyond 2 h/d hastened the response but did not improve outcome. More than 80% of the improvement during occlusion occurred within 6 weeks. Treatment outcome was significantly better for children younger than 4 years (n 17) than in those older than 6 years (n 24; P 0.0014). CONCLUSIONS. Continuous objective monitoring of the amount of patching therapy received has provided insight into the dose–response relationship of occlusion therapy for amblyopia. Patching is most effective within the first few weeks of treatment, even for those in receipt of a relatively small dose. Further studies are needed to elucidate the neural basis for the dose–response functions. (Invest Ophthalmol Vis Sci. 2004;45: 3048 –3054) DOI:10.1167/iovs.04-0250

Treatment dose-response in amblyopia therapy: the Monitored Occlusion Treatment of Amblyopia Study (MOTAS).

Aim: To describe the visual response to spectacle correction (“refractive adaptation”) for children with unilateral amblyopia as a function of age, type of amblyopia, and category of refractive error. Method: Measurement of corrected amblyopic and fellow eye logMAR visual acuity in newly diagnosed children. Measurements repeated at 6 weekly intervals for a total 18 weeks. Results: Data were collected from 65 children of mean (SD) age 5.1 (1.4) years with previously untreated amblyopia and significant refractive error. Amblyopia was associated with anisometropia in 18 (5.5 (1.4) years), strabismus in 16 (4.2 (0.98) years), and mixed in 31 (5.2 (1.5) years) of the study participants. Mean (SD) corrected visual acuity of amblyopic eyes improved significantly (p Conclusion: Refractive adaptation is a distinct component of amblyopia treatment. To appropriately evaluate mainstream therapies such as occlusion and penalisation, the beneficial effects of refractive adaptation need to be fully differentiated. A consequence for clinical practice is that children may start occlusion with improved visual acuity, possibly enhancing compliance, and in some cases unnecessary patching will be avoided.

https://bjo.bmj.com/content/bjophthalmol/88/12/1552.full.pdf

Refractive adaptation in amblyopia: quantification of effect and implications for practice.

The natural history of retinopathy of prematurity (ROP) has been studied prospectively in 572 infants 1,700 g birthweight using a protocol designed specifically to investigate the subtle features of this condition. Acute ROP developed in 50.9%. All ROP stages 1 and 2 underwent complete resolution and of the 27 (4.7%) infants with stage 3/4 disease, cicatricial sequelae developed in six. Incidence and severity increased with decreasing birthweight and gestational age. Onset was not confined to the temporal retina but exhibited a predilection to start first in the nasal retina of the most immature neonate. The vertical retinal regions were relatively spared. Retinal arteriolar tortuosity developed around three months postnatally and was related to ROP severity but not its presence. The age at onset and rate of progression of retinopathy were largely determined by the stage of development but were also modified by systemic and local factors. The relevance of these findings to ROP screening is discussed.

/pdf/natural-history-of-retinopathy-of-prematurity-a-prospective-3v5vrpxz0o.pdf

Natural history of retinopathy of prematurity: a prospective study.

PURPOSE To identify factors that influence the outcome of treatment for unilateral amblyopia, as a part of the Monitored Occlusion Treatment of Amblyopia Study (MOTAS). METHODS This was an intervention study consisting of three nonoverlapping phases: "Baseline", "refractive adaptation" (18 weeks of full-time spectacle wear), and "occlusion" (6 hours of patching per day, objectively monitored). Condition factors: type of amblyopia, age of participant, initial severity of amblyopia, fixation, and binocular vision status; treatment factors: refractive adaptation and occlusion (total dose [hours] and dose rate [hours per day]) were assessed for their influence on visual outcome. Visual outcome was expressed in three ways: logMAR (logarithm of the minimum angle of resolution) change, residual amblyopia, and proportion of the deficit corrected. RESULTS The study included 85 participants (mean age, 5.1 +/- 1.4 years) with amblyopia associated with strabismus (n = 32) or anisometropia (n = 20) or associated with both anisometropia and strabismus (n = 33). Treatment factors: cumulative occlusion dose exceeding 50 hours, and dose rates > or =1 hour per day resulted in (P < or = 0.01) lower residual amblyopia and a greater proportion of the deficit corrected. Condition factors associated with poor outcome (high residual amblyopia) were presence of eccentric fixation, severe initial amblyopia, and no binocular vision. CONCLUSIONS Factors influencing outcome with treatment for amblyopia are occlusion dose (the rate of delivery and cumulative dose worn), the initial severity of the amblyopia, binocular vision status, fixation of the amblyopic eye, and the age of the subject at the start of treatment.

Alistair R. Fielder

Papers

Treatment dose-response in amblyopia therapy: the Monitored Occlusion Treatment of Amblyopia Study (MOTAS).

Refractive adaptation in amblyopia: quantification of effect and implications for practice.

Natural history of retinopathy of prematurity: a prospective study.

Treatment of unilateral amblyopia: factors influencing visual outcome.

Remediation of refractive amblyopia by optical correction alone