Josef Wollensak

Myopic Photorefractive Keratectomy with the Excimer Laser: One-year Follow-up

To evaluate the efficacy, predictability, and stability of myopic photorefractive keratectomy (PRK), the authors completed a 1-year follow-up study on a consecutive series of 26 sighted eyes undergoing this procedure. The results of this follow-up are presented. In addition, side effects and complications in another 255 sighted eyes with a follow-up of 3 months to 1 year are reported to judge the safety of the procedure. Twenty-four of 26 eyes (92%) were within +/- 1.0 diopter (D) of the intended final refraction (baseline, -1.4 to -9.25 D). Fifty-eight percent of the eyes were stable within +/- 0.25 D between 6 and 12 months. One year after surgery, none of the patients lost or gained more than one line of best corrected (spectacle) visual acuity. Uncorrected visual acuity improved to 20/40 or better in 96% of the eyes and to 20/20 or better in 48% of the eyes (not including the eyes that were intentionally undercorrected). However, visual acuity with glare decreased from 20/27 preoperatively to 20/31 after 1 year. Scarring occurred in 2.8% of the treated corneas. Risk factors for scarring include noncompliance with postoperative steroid medication, high myopic corrections, and high steroid responders (3.1%). Collagen vascular and other autoimmune diseases are a contraindication for PRK.

Excimer laser keratectomy for correction of astigmatism.

We treated 13 eyes (12 patients) with excimer laser surgery for correction of astigmatism using linear corneal T-excisions. All eyes were followed up for a minimum of three months. We used a newly developed delivery system and special contact masks to deliver the 193-nm excimer light. Astigmatic corrections of up to 4.16 diopters were obtained. The actual corrections corresponded well with the intended values as predicted by a biomechanical theory. The refractive change over time was different than that observed after knife incisions, suggesting different repair mechanisms. An epithelial plug filling the whole T-excision persisted for over one year in all eyes.

Comparison of a diffractive bifocal and a monofocal intraocular lens

Purpose: To compare a Pharmacia diffractive bifocal intraocular lens (IOL) with a monofocal lens of the same design without the diffractive grating. Setting: . Multicenter study. Methods: This randomized, prospective study comprised 70 patients with a monofocal IOL and 79 with a diffractive bifocal IOL. Follow‐up was 5 to 6 months. Near and distance visual acuities, contrast sensitivity, patient satisfaction, and spectacle use were evaluated. Results: All patients achieved a best corrected visual acuity of 0.5 or better; 80% in the monofocal and 71 % in the bifocal group had a best corrected visual acuity of 1.0 or better. Without correction, 93% of the bifocal and 9% of the monofocal group could read J3 or better. With distance correction, 99% and 4%, respectively, could read J3 or better. Contrast sensitivity was slightly lower in the bifocal group at distance and near for all spatial frequencies. In the bifocal group, 46% never used spectacles for near tasks. Overall satisfaction was rated good by 86% of the monofocal and 85% of the bifocal group. Conclusions: The diffractive bifocal IOL performed well at distance and near. Patients who no longer require spectacles will benefit significantly from a bifocal IOL, but many with a bifocal IOL in one eye will require spectacles for the fellow eye.

Effect of heparin surface modification of polymethylmethacrylate intraocular lenses on signs of postoperative inflammation after extracapsular cataract extraction. One-year results of a double-masked multicenter study.

PURPOSE A heparin surface modified posterior chamber intraocular lens (IOL) was compared with a conventional polymethylmethacrylate (PMMA) IOL regarding postoperative complications caused by inflammation. METHODS Five hundred twenty-four patients from 10 different centers were included in a parallel group, double-masked, multicenter study. RESULTS The cumulative number of patients with inflammatory cellular deposits on their IOLs during the first postoperative year differed significantly in favor of the heparin surface modified group, with 29.8% of the patients having cellular deposits compared with 48.8% of patients in the control group. Cellular deposits were observed most frequently at 3 months after surgery, and the difference between the groups was most pronounced and statistically significant at this time. The same results were seen at 1 year, but the difference was not significant. The number of cellular deposits per patient, however, was significantly lower in the heparin surface modified group at 1 year. Cumulatively, there were significantly more patients with posterior synechiae in the PMMA group than in the heparin surface modified group during the 1-year follow-up. Complications were few and comparable between the groups. CONCLUSION The results of this study indicate that heparin surface modification reduces the inflammatory response to PMMA IOLs.

Protein changes in the human lens during development of sentile nuclear cataract

Senile nuclear cataractous lenses were divided into three groups of increasing nuclear color. These groups were considered as successive stages in the development of senile nuclear cataract. The cortex and the nucleus of normal and cataractous lenses were separated into water-soluble, urea-soluble and urea-insoluble fractions. Fractionation on a Sephadex G-200 column of the water-soluble components revealed five protein fractions for both cortex and nucleus. Only minor quantitative differences in polypeptide chain composition were found by isoelectric focusing between corresponding protein fractions isolated from normal and cataractous lenses. The weight percentages of the water-soluble, urea-soluble, and urea-insoluble fractions of cortex and nucleus from the normal and cataractous lenses were determined. A decrease of the amounts of the water-soluble and urea-soluble fractions and a concomitant increase of the urea-insoluble fraction were observed in the nucleus as a function of cataract development. Lens wet weight and protein content did not change significantly. The carbohydrate content of the urea-soluble fractions increased, that of the urea-insoluble fraction decreased. A striking decrease of the phospholipid content in the urea-insoluble fraction was found.

The polypeptide chains of α-crystallin from old human eye lenses☆

Abstract The polypeptide chains of α-crystallin from 60- to 80-year-old human eye lenses were studied to determine whether they are subject to similar post-synthetic alterations as known from bovine α-crystallin. Isoelectric focusing in the presence of 6 M urea revealed that old human α-crystallin consists of five major polypeptide chains, designated as Ax, A2, Bx, By and B2. By dodecyl sulphate gel electrophoresis mainly chains with apparent molecular weights of 22 000 and 20 000 were observed. Ion-exchange chromatography in the presence of urea was applied to obtain enriched preparations of individual polypeptides. Additional data concerning the primary structure of some chains were gathered by tryptic peptide mapping in combination with amino acid analysis. The presence of two cysteine residues in the A-chains was demonstrated. The Ax component turned out to be composed of two chains: deamidated A2 of normal length (172 residues) and, presumably, a shortened A2-chain: A21–151. The Bx- and By-chain with isoelectric points slightly lower and higher, respectively, than that of bovine B1, appeared to be B21–170 and deamidated B2 of normal length (175 residues). A group of polypeptides with very acidic isoelectric points, present in low proportion, showed a heterogeneous molecular weight distribution below 18 000 and a high degree of similarity with the A-chains as judged by tryptic peptide mapping. In spite of several differences in subunit composition, it can be concluded that in human α-crystallin, as in bovine α-crystallin, deamidation and degradation processes occur.

NMR-Tomographie des menschlichen Auges

The NMR relaxation data of tissue are the basis of an appropriate adjustment of NMR imaging parameters. The relaxation data of ocular tissues are presented, and the relaxation behaviour of the eye is discussed. NMR imaging of eyes with intraocular silicone and pseudophakia are shown. Up to the present time, neuritis of the optic nerve is not detectable by NMR tomography whereas intraocular melanoma are clearly distinguishable.

Variation in proportion and molecular weight of native crystallins from single human lenses upon aging and formation of nuclear cataract

Extracts of water-soluble proteins from cortex and nucleus of single human lenses have been analyzed by high-pressure gel permeation chromatography in combination with a size- and a concentration-sensitive detector. Using this rapid and accurate method, changes in molecular weight and proportion of the native crystallins upon aging and formation of nuclear cataract are observed. In the range from 30 to about 40 years the gamma-crystallin content of normal lenses increases and that of alpha-crystallin decreases; over 40 years the level of gamma-crystallin decreases and that of alpha-crystallin remains constant in the cortex (11%) as well as in the nucleus (1-2%). These changes are accompanied by an increase in the water-insoluble fraction. With progressing nuclear cataract an increase in beta 3- and a drastic decrease in gamma-crystallin content, especially in the nucleus, are accompanied by a steep increase in the water-insoluble fraction. The molecular weights of the crystallins do not change significantly, except that of alpha- and beta 1-crystallin which show an increase with age.

Ciliary Block (Malignant) Glaucoma Following Posterior Chamber Lens Implantation

Ciliary block (malignant) glaucoma is a rare complication of cataract surgery. In eyes with narrow angles and acute glaucoma, ciliary block must be differentiated from pupillary block to provide appropriate therapy. We review two cases of ciliary block glaucoma following uncomplicated extracapsular cataract extraction with posterior chamber lens implantation. Previous filtering procedures in these cases resulted in protracted shallowing of the anterior chamber, possibly contributing to the pathogenesis of ciliary block. In addition, the operative trauma of cataract surgery may have resulted in the separation of the vitreous base from the pars plana. Misdirected aqueous humor then could have entered the vitreous body, displacing the iris-pseudophakos diaphragm forward, and resulting in the acute glaucoma. Vitrectomy, which resolved the acute glaucoma, is valuable in treating ciliary block glaucoma.

Contrast sensitivity after implantation of diffractive bifocal and monofocal intraocular lenses

Purpose: To compare contrast sensitivity (CS) after implantation of a diffractive bifocal intraocular lens (IOL) and a monofocal IOL of similar design. Setting: Seven European centers. Methods: In this randomized, prospective study, CS was tested 5 months after cataract and IOL implantation surgery in 115 patients with a diffractive bifocal IOL and 106 patients with a monofocal IOL. It was also tested in a subgroup of 38 patients who had bilateral implantation of a diffractive bifocal IOL. Contrast sensitivity was tested using the Vision Contrast Test System (VCTS). Results: In patients with a best corrected visual acuity (BCVA) of 1.0 or better, the CS at all spatial frequencies (1.5 to 18 cycles/degree), both at distance and near, was slightly lower in the bifocal IOL group than in the monofocal group. Mean values were within the normal range. In patients with a BCVA of less than 1.0, the CS was lower and the difference between the bifocal and monofocal groups was less. In patients with bilateral bifocal IOLs, CS was better when tested bilaterally than when testing the better eye alone. Pupil size affected the results to a small degree. Contrast sensitivity appeared to improve over time after implantation of a diffractive bifocal IOL. Conclusions: In patients with cataract and no other eye pathology, the diffractive bifocal IOL will slightly reduce the CS at all spatial frequencies. In those with reduced visual acuity after cataract surgery, CS will be reduced accordingly. In this situation, the reduction from the diffractive bifocal optic would be minor.