Refractive errors (myopia, hyperopia, and astigmatism) are complex heterogeneous disorders of the human eye and are ideal for genetic investigation. Moderate to severe refractive errors can predispose individuals to poor visual development, various types of glaucoma, misshapen corneal surfaces, premature cataracts, and loss of retinal integrity, which can lead to detachment. Knowledge of genetic mechanisms involved in refractive error susceptibility may allow treatment to prevent progression or to further examine gene-environment interactions. Early genetic predisposition detection for developing severe refractive errors may be useful for efficient and cost-effective screening program design. This review explores the genetic mechanisms associated with nonsyndromic refractive error development known to date.

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Complex trait genetics of refractive error.

Purpose To compare the ophthalmic viscoelastic device (OVD) Healon®5 (sodium hyaluronate 2.3%) with 4 other commonly used OVDs during phacoemulsification and intraocular lens implantation in terms of influence on intraocular pressure (IOP) postoperatively and endothelial cells preoperatively and postoperatively. Setting Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Germany. Methods This clinical randomized prospective study, in which patients and observer were masked, comprised 81 eyes. Seventy-four eyes (mean patient age 71.2 years ± 7.8 [SD]) completed all preoperative and 5 postoperative examinations. The OVDs used were OcuCoat® and Celoftal® (hydroxypropyl methylcellulose 2.0%), Viscoat® (sodium hyaluronate 3.0%–chondroitin sulfate 4.0%), Healon GV® (sodium hyaluronate 1.4%), and Healon5 (sodium hyaluronate 2.3%). Intraocular pressure was measured by standard Goldmann applanation tonometry preoperatively and 4 to 6 and 24 hours and 7, 30, and 90 days postoperatively. Endothelial cell counts were done preoperatively and 90 days postoperatively using a Pro/Koester WFSCM contact endothelial microscope. Exclusion criteria were IOP greater than 21 mm Hg at the preoperative examination, age younger than 40 years, significant corneal pathology, and a history or presence of uveitis or pseudoexfoliation syndrome. Results All groups had increased IOP 4 hours postoperatively. The Healon5 group had the highest mean pressure (24.9 mm Hg) followed by the Viscoat group (23.6 mm Hg). The mean IOP in the other OVD groups was less than 22.1 mm Hg. These differences were not significant. Twenty-four hours postoperatively and at all subsequent examinations, mean IOP was below 20 mm Hg. The Healon5 group had the lowest mean endothelial cell loss (6.2%), significantly lower than in the other groups ( P Conclusion With all 5 OVDs, endothelial cell loss was found, with the lowest in the Healon5 group, and IOP was increased 4 to 6 hours postoperatively. After 24 hours, no significant increases in IOP were noted.

Effect of Healon5 and 4 other viscoelastic substances on intraocular pressure and endothelium after cataract surgery.

Purpose: To investigate the effect on intraocular pressure (IOP) of sutureless scleral and corneal tunnel Kelman phacoemulsification (KPE) with foldable posterior chamber intraocular lens (IOL) implantation. Setting: Jules Stein Eye Institute, Los Angeles, California, USA. Methods: Preoperative and postoperative (: and 6 weeks and 6 to 8 months) IOP measurements of 385 consecutive eyes. having uneventful phacoemulsification and foldable posterior chamber IOL implantation were reviewed retrospectively. A subset of 193 eyes for which no IOP measurements were missing at any follow-up were analyzed separately. Results: Mean preoperative IOP was 1,5.8 mm Hg ± 0.2 (±SE). It dropped postoperatively by 1,3 ± 0.2 mm Hg at 1 week ( P P P P P Conclusion: Sutureless KPE with foldable posterior chamber IOL implantation lowered IOP by 1.1 to 2.5 mm Hg for the 6 months immediately following surgery. Glaucoma patients had a statistically significant initial rise in IOP at 1 week.

Intraocular pressure change after sutureless phacoemulsification and foldable posterior chamber lens implantation.

This chapter reviews medical applications of a variety of mid-infrared lasers. These applications are based on strong absorption of laser light in human tissue due to the presence of naturally occurring chromophores, specific and unspecific absorbers. Medically relevant laser-tissue interactions are described. Experimental data, obtained with free electron lasers describe photoablation quantitatively in the mid-IR as well as collateral adverse effects. Feedback technologies for online therapy control are presented; they enhance the selectivity of the laser—tissue interaction. Typical medical and surgical applications in gynecology, otorhinolaryngology, neurosurgery, dermatology, urology, dental surgery, ophthalmology and cardiovascular surgery are briefly summarized.

Mid-IR Laser Applications in Medicine

Purpose To evaluate the effect of Healon®5 (sodium hyaluronate) and Viscoat® (sodium chondroitin sulfate–sodium hyaluronate) on intraocular pressure (IOP) after bilateral small incision cataract surgery. Setting Department of Ophthalmology, University of Vienna, Vienna, Austria. Methods This prospective randomized study comprised 70 eyes of 35 consecutive patients with age-related cataract in both eyes scheduled for bilateral small incision cataract surgery. The patients were randomly assigned to receive Healon5 or Viscoat during cataract surgery in the first eye. The second eye received the other viscoelastic substance. Cataract surgery was performed in an identical fashion in both eyes, with a temporal 3.5 mm sutureless posterior limbal incision, phacoemulsification, and implantation of a foldable silicone intraocular lens. The IOP was measured preoperatively and 6 hours, 20 to 24 hours, and 1 week postoperatively. Results At 6 hours after surgery, the mean IOP increased by 5.2 mm Hg ± 5.3 (SD) in the Healon5 group ( P P P = .0016). Intraocular pressure spikes of 30 mm Hg or more occurred in 2 eyes in the Healon5 group and in 10 eyes in the Viscoat group ( P = .0112). Twenty to 24 hours and 1 week postoperatively, the mean IOP in the 2 groups was not statistically different. Conclusions Viscoat caused a significantly higher IOP increase and significantly more IOP spikes than Healon5 in the early period after small incision cataract surgery.

Intraocular pressure after small incision cataract surgery with Healon5 and Viscoat.

Purpose: To evaluate transient increases in intraocular pressure (IOP) after use of high-viscosity viscoelastic agents in cataract surgery. Setting: Military Hospital, Ulm, Germany. Methods: In a prospective, randomized study, we evaluated IOP following cataract surgery using two different viscoelastic substances (Healon®, Healon® GV). The viscosity of Healon GV is 10 times higher than that of Healon because of higher concentration and molecular weight. Patients having identical phacoemulsification procedures (sutureless clear corneal tunnel incision with foldable silicone lens implantation) (N = 60) and identical viscoelastic removal were assigned to groups of 15 based on viscoelastic used and removal time (20 or 40 seconds). Intraocular pressure was measured preoperatively and at 6, 24, 36, and 48 hours and 1 month postoperatively. Results: The highest mean IOP elevations in both viscoelastic groups were obtained at 24 hours postoperatively (2.9 mm Hg ± 4.3 [SD] with Healon and 3.3 ± 6.3 mm Hg with Healon GV). There were no statistically significant differences between the two viscoelastics and the two removal times during the entire follow-up period (unpaired t-test), but standard deviations were higher in the Healon GV groups at 6 and 24 hours. Two patients in the Healon groups and three in the Healon GV groups required medical treatment for IOP within the first 24 postoperative hours; however, all five patients had an IOP lower than 22 mm Hg on the second postoperative day. Conclusions: Based on postoperative IOP, both viscoelastics can be equally well removed from the anterior chamber. Incidence of high IOP using high-viscosity hyaluronic acid is minimized by the described removal technique.

Evaluation of intraocular pressure with Healon and Healon GV in sutureless cataract surgery with foldable lens implantation

Background Viscoelastic substances are used in anterior segment surgery to reduce tissue trauma and endothelial cell loss and to serve as space maintainer Healon®GV ( greater viscosity), a hyaluronic acid product with a ten times higher viscosity than Healon®, is utilized in complicated procedures (vitreous pressure, flat anterior chamber, congenital cataracts, etc) and often in phacoemulsification Intraocular pressure (IOP) rise following incomplete removal is a known problem Materials and methods A prospective randomized study was performed to evaluate the IOP following cataract surgery with Healon® or Healon®GV and different removal times (RT) Forty patients (forty eyes) having uncomplicated phacoemulsification with foldable silicone posterior chamber lens implantation and identical viscoelastic removal technique were assigned to four groups : Healon® with 20 or 40 seconds (sec) RT, Healon®GV with 20 or 40 sec RT All surgeries were performed by the same surgeon using the same technique especially for the removal of the viscoelastic All patients had an identical pre- and postoperative medication Intraocular pressures were obtained using Goldman's applanation tonometry preoperatively, six, 24, 36, and 48 hours postoperatively Results The IOP follow-up showed no significant difference between the two viscoelastic substances and the two different removal times of 20 and 40 sec (t-test) In four patients (two of the Healon®-groups, two of the Healon®GV-groups) the IOP required treatment On the second postoperative day, the same four patients showed IOP lower than 22 mm Hg The highest mean-IOP (mm Hg) in both Healon-groups was obtained at 24 hours postoperatively: 185±39 SD (Healon®) ; 173±59 SD (Healon®GV) Conclusion The incidence of postoperative rise in IOP using high viscosity hyaluronic acid (Healon®GV) can be minimized by the applied removal technique Both viscoelastics - despite of higher molecular weight and viscosity - can be removed equally from the anterior chamber following phacoemulsification and posterior chamber lens implantation utilizing IOP as a parameter in vivo

Postoperative intraocular pressure in the first days after intraocular administration of hyaluronic acid solution with different viscosities

Background Cornea plana is an extremely rare, congenital hereditary malformation of the corneo-scleral shape The curvatures of cornea and sclera are nearly equal with an indistinct limbus In addition to the flatness, there is a peripheral sclerocornea that produces a pseudomicrocornea The low corneal refraction and the short anterior segment often result in hyperopia Myopia is also described Usually the posterior segment is not involved Materials and Methods A young man of 22 years, his three-and five-year-old sons, and his newborn daughter showed this hereditary abnormality of the cornea In this uncommon anomaly we measured corneal curvature, refraction, diameter and in three of the four patients echographical length of the bulbi Results The family showed an autosomal dominant inheritance of the cornea plana The corneal refraction was less than 32 diopters The scleral encroachment caused an oval cornea measuring horizontally between 5 and 65 mm, vertically 4 to 5 mm Additionally a pseudoblepharoptosis and a conjunctival xerosis of the father and his sons was observed, which is not regularly found A-scan measuring of the bulbi revealed age-related normal values Conclusions There is no evidence for progression of this anomaly during life No therapeutical consequences are necessary To preserve a satisfactory function a conscientious orthoptical maintainance should be guaranteed

Kongenitale familiäre Cornea plana mit Ptosis, peripherer Sklerokornea und Bindehaut-Xerose

OBJECT Results over a period of 24 months of performing the Er:YAG laser ab externo sclerostomy. MATERIAL AND METHODS The procedure was performed 81 times (chronic glaucoma with open angle (n = 55) and narrow angle (n = 15), 6 secondary glaucoma, 4 pigment glaucoma, 1 normal pressure glaucoma) in 74 eyes of 64 patients at the age of 70 +/- 10 years without any peribulbar anesthesia. The pulse energy was 11 mJ with a repetition rate of 7 Hz. Antimetabolites were not applicated. Success was defined as an IOP of less than 22 mm Hg or a decrease of at least 30%, with or without anti-glaucoma medication. RESULTS The mean IOP of all cases decreased from preoperatively 28 +/- 8.1 mm Hg (Success group: 26.7 +/- 7.3 mm Hg) to 15 +/- 8.4 mm Hg (Success group: 14.6 +/- 7.8 mm Hg) on the first postoperative day. The success rate was about 50% within the period of two weeks to six months and decreased to about 15% in the 24th month. Complications were iris incarceration/synechia (n = 33), hypotony (n = 36) with consequent choroidal detachment (n = 8), hyphema (n = 19) and more pronounced inflammation symptoms (n = 10). In most cases, the early postoperative outflow failure is caused by iris incarceration into the internal ostium. The scarring tendency of the episcleral tissue leads to closure of the external ostium after months. Resurgery was necessary in 26 cases. CONCLUSIONS Further efforts should be directed to maintain the intact corneoscleral morphology of the canal, created by an optimized method of the surgical technique. The application of antimetabolites in correct dosage or the implantation of modified silicon draining systems would be helpful.

Ab-externo-Sklerostomie mit dem Er:YAG-Laser: Ergebnisbericht nach zwei Jahren

Background Ab externo sclerostomy enables the restrained aqueous humour drain via a microgram wide corneoscleral canal into the subconjunctival space being an alternative surgical method in glaucoma therapy. The tissue ablative infrared laser radiation (2.94 microgram) was applied until now via a quartz fiber manually pushed forward in permanent tissue contact. Our aim was the development of a new applicator tip without manual feed in order to achieve a reduction in times for construction and maintenance of the former tip as well as in the risk of an infection and mechanical damage of intraocular structures. Material and method In pig eye experiments, the laser parameters were varied in histological and scanning electron microscopic evaluation (pulse energy: 10-60 mJ, repetition rate: 5-17.5 Hz, combinations of constant power: 200 mW). Their influence on the canal shape and the morphology of the internal ostium has been proven in special tests. Results The new development of the applicator tip (core diameter: 550 microgram) enables a conical profile of the beam (diameter 500-150 microgram) within a distance of 2-3 mm, now without pushing the fiber forward ("fixed fiber"). Smooth canal surfaces, a small homogeneous necrosis zone (25 microgram) and only few tissue ruptures have been seen histologically and on SEM. The correlations of ablation rates/-speed as well as canal characteristics are more significant to energy densities than to repetition rates. First clinical application was technically successful. Conclusions The new applicator tip optimizes the method of Er: YAG-laser ab externo sclerostomy from the technical and surgical point of view.

Eberhard Schütte

Papers

Evaluation of intraocular pressure with Healon and Healon GV in sutureless cataract surgery with foldable lens implantation

Postoperative intraocular pressure in the first days after intraocular administration of hyaluronic acid solution with different viscosities

Kongenitale familiäre Cornea plana mit Ptosis, peripherer Sklerokornea und Bindehaut-Xerose

Ab-externo-Sklerostomie mit dem Er:YAG-Laser: Ergebnisbericht nach zwei Jahren

[Modified radiation administration in Er:YAG laser ab externo sclerostomy].