Nutritional supplementation to prevent cataract formation

Age-related cataract (ARC) is the leading cause of blindness in the world, particularly in developing countries. In contrast, cataract surgery has become the most frequent surgical procedure in people aged 65 years or older in the Western world, causing a considerable financial burden to the health care system. The development of cataracts is mainly an age-related phenomenon, although socioeconomic and lifestyle factors appear to influence their development, e.g. smoking has been found to directly influence ARC. A key role in the pathomechanism of the crystalline lens alteration is played by glucose metabolism and associated effected redox potential, which may induce oxidative damages. Aldose reductase blockers were able to prevent the development of diabetic cataracts in experimental studies, however clinical trials were interrupted due to unclear side effects. Other drugs with radical scavenging properties were effective in in vitro and in vivo experiments, but could not be proven to be efficient and safe in preclinical human trials. A number of epidemiological studies showed an increased risk of nuclear or cortical cataract in people with low blood levels of vitamin E. It is also known that the measured levels of ascorbic acid decline with increasing age in the lens. Beta-Carotin and other non-polar carotenoids seem to be missing and may therefore only play a minor role. Polarized carotenoid lutein and zeaxanthin are available in low concentrations and may therefore have some direct effects. The results of the present interventional studies are still controversial. While the Linxian studies indicated that the prevalence for nuclear cataract was reduced by the supplementation with retinol/zinc or vitamin C/molybdenum, the AREDS trial showed no effect of the antioxidant formulation on the development or progression of ARC. Again, while the REACT study demonstrated a statistically significant positive treatment effect 2 years after treatment for the US patients and for both subgroups (US & UK) after 3 years, no effect was observed in UK patients alone. In another US study, the Physician Health Study, no positive or negative effect of Beta-carotin was observed. Taken together, these studies suggest that any effect of antioxidants on cataract development is likely to be very small and probably is of no clinical or public health significance, thus removing a major rationale for 'anticataract' vitamin supplementation among health-conscious individuals.

[Reduction of decentration after LASIK using a modified eye tracker ring for the MEL-70 excimer laser]

BACKGROUND

The aim of this study was to determine and compare the rate of eccentric laser ablation after LASIK depending on the eye tracker ring used.

PATIENTS AND METHODS

All LASIK treatments were carried out using the MEL-70 flying spot excimer laser (Zeiss-Meditec, Jena). The flap was produced using a Corneal Shaper trade mark or Hansatome trade mark Microkeratome (B and L Surgical, Heidelberg). Initially we used an 11 mm eye tracker ring without hinge protector. At the end of February 2001 this ring was replaced by a 10 mm and a 9.5 mm ring with built-in hinge protector. An additional modification was introduced by us: at 1 mm separations little teeth-like spikes were engraved into the eyeward side of the ring, thus stabilising the position of the ring on the globe and allowing free liquid to flow through the spaces between each spike. The built-in calibration system of the corneal topography (TMS 3, Tomey, Erlangen) from patients with a follow-up of one month or longer was used to determine the distance between the centre of the ablation zone from the fixation point.

RESULTS

In group I patients (old ring) 42 eyes were treated. In 4 eyes ablation was perfect, in 21 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 11 eyes 0.51 to 0.99 mm and in 5 eyes 1.1 to 1.49 mm whereas one eye showed a decentred ablation of 1.53 mm. In group II (new ring) 42 eyes were investigated also. In 11 eyes ablation was perfect, in 20 eyes the ablation centre was located 0.1 to 0.49 mm from the fixation point, in 10 eyes 0.5 to 0.99 mm and one eye had an eccentric ablation of 1.28 mm from the fixation point.

CONCLUSION

The further development of our eye tracker ring for the MEL-70 laser considerably reduced the rate of decentred ablations. An enhanced grip of the ring onto the globe reduces a slow slide during the laser procedure.

Evaluation of Granular Corneal Dystrophy With Optical Coherent Tomography

OBJECTIVE

To determine the intrastromal layer of corneal deposits in granular corneal dystrophy (GCD).

DESIGN

Investigative case report.

METHODS

A 32-year-old woman with bilateral decreased vision because of corneal deposits was examined with cross-sectional scans using optical coherence tomography (OCT).

RESULTS

Visual acuity was 20/100 OU. Multiple confluent gray-white patches with an irregular shape were seen in the corneal stroma, leading to a diffuse opacification. OCT disclosed multiple hyperreflective dots in the anterior and deeper stromal layers.

CONCLUSION

When severe corneal opacities obscure the clinical differentiation between anterior and deep infiltrates, OCT may determine the layers of the accumulation and select an appropriate surgical procedure.

Inzisionale Astigmatismusbeeinflussung bei der Implantation von phaken 6-mm-Irisklauenintraokularlinsen

BACKGROUND

The implantation of a phakic 6-mm-iris-claw intraocular lens requires a 6.1-6.2 mm incision. This induces a variable amount of corneal astigmatism depending on the location and the type of the incision used. The aim of the current study is to investigate the surgically induced astigmatism (SIA) of different incision types and locations. This should help to achieve nearly spherical postoperative refraction.

PATIENTS AND METHOD

28 eyes of 16 patients with a 1-year follow-up after an implantation of a 6-mm-non-foldable iris-claw phakic IOL were studied. 5 different incision techniques were used. These were a superior corneal incision alone (8 eyes) or in combination with a 60 degrees limbal relaxing incision (LRI) at the same axis (8 eyes), a superior sclerocorneal tunnel incision (6 eyes) and the two-incisional approach either with a sclerocorneal (4 eyes) or a pure corneal (2 eyes) main temporal incision. The SIA was calculated for each incision used.

RESULTS

The superior corneal incision had a mean SIA of 1.2 D cyl. This SIA was enhanced by an opposite LRI by another 1 D cyl. The sclerocorneal tunnel induced 0.75 D cyl, while the two-incisional techniques delivered nearly astigmatismus neutral results.

CONCLUSION

A proper selection of an appropriate incision site and type allows to correct the preexisting astigmatism or to keep a spherical refraction after an implantation of a 6-mm-rigid phakic iris-claw IOL.

Vermessung der skotopischen Pupille

PURPOSE

The aim of the study was to compare the accuracy and the reproducibility of scotopic pupil measurements using two different methods.

PATIENTS AND METHODS

We developed a simple test to measure scotopic pupil diameters using a narrow slit of light through a green filter of the Haag-Streit slitlamp. A total of 100 eyes from 50 refractive surgery candidates were prospectively examined by 2 independent investigators using both the Colvard pupilometer (Oasis/USA) and Sekundo's slitlamp green light test. Results were compared using all pairwise multiple comparison procedures (Student-Newman-Keuls method, SigmaStat/Jandel Scientific). The mean age of the patients was 36.3 years with a male:female ratio of 16:34. The colour of the iris was considered blue for 36 individuals and brown for the remainder.

RESULTS

Reproducibility: the right eye mean pupil diameter using Sekundo's method was 6.4 mm (+/-0.9) measured by both the first (Slit 1R) and the second (Slit 2R) investigator. The left eye mean pupil diameter was 6.5 mm (+/-1) (Slit 1L) and 6.35 mm (+/-1) (Slit 2L), respectively. The following measurements were obtained with the Colvard pupillometer: (Colv1R)=6.25+/-0.85 mm, (Colv2R)=5.99+/-1 mm, (Colv1L)=6.15+/-0.91 mm, (Colv2L)=6.05+/-0.9 mm. There were no statistically significant differences between the two investigators within the same method of examination. Comparability:The data of both investigators were combined to form 4 groups: (Slit R)=6.4+/-0.96 mm, (Slit L)=6.4+/-1 mm, (Colv R)=6.05+/-0.9 mm, (Colv L)=6.1+/-0.93 mm. There was a significant difference ( p=0.024) between the two methods for both right and left eyes. Particularly for large pupils, the slitlamp green light measurements were significantly higher (up to 0.35 mm) than those with Colvard's device.

CONCLUSIONS

The slitlamp green light test provides similar reproducibility for the measurement of the scotopic pupil diameter as the commercially available Colvard pupilometer.

[Wavefront analysis and adaptive optics]

In this paper we attempt to provide an overview of the principles of wavefront measurement. We also discuss the operational principles of different systems currently present on the market including their advantages and disadvantages. Moreover, we speculate on current and possible future implications of this new technology in the laser refractive surgery. Adaptive optics are explained in the context of "customized ablation" and preoperative verification of the desired results. Finally, the first international clinical results of wavefront guided excimer laser surgery are reviewed and critically commented.

[Laser-assisted subepithelial keratectomy (LasEk). Review of the current state of knowledge]

This article offers an overview of the current state of knowledge on the results and techniques of the evolving refractive procedure called laser-assisted subepithelial keratectomy (LasEk). A few peer-reviewed published clinical and experimental studies on this new technique are critically debated. Furthermore we discuss the indications for this procedure in comparison to photorefractive keratectomy (PRK) and laser in situ keratomileusis (Lasik) based on the current body of literature and the first author's clinical and scientific personal experience.

Six-year follow-up of laser in situ keratomileusis for moderate and extreme myopia using a first-generation excimer laser and microkeratome

PURPOSE

To evaluate objectively and subjectively the long-term outcome of laser in situ keratomileusis (LASIK) in patients with high and very high myopia.

SETTING

Department of Ophthalmology, Philipps University, Marburg, Germany.

METHODS

Thirty-three eyes of 19 patients were followed for a mean of 76 months (range 50 to 84 months) after primary LASIK using the Keratom I excimer laser (Schwind) and the ALK microkeratome (Chiron). Refraction, glare, pachymetry, corneal topography, and tear-film secretion and stability were measured. At the last examination, patients also answered a 14-item questionnaire.

RESULTS

Preoperatively, the mean spherical equivalent was -13.65 diopters (D). At 1 year, it was -0.25 D and after 6 years, -0.88 D. Fifteen percent of eyes lost > or =2 lines of best spectacle-corrected visual acuity (BSCVA), and 9% gained > or =2 Snellen lines. At the end of the study, 46% of eyes were within +/-1.0 D of the attempted corrected and 88% were within +/-3.0 D. There were 5 microkeratome-associated complications; 3 resulted in loss of BSCVA. The latest pachymetry showed a mean corneal thickness of 498.5 microm (range 396 to 552 microm). There were no cases of keratectasia. Seventy-five percent of patients noted an increase in their quality of life. Seventy-one percent were satisfied with their postoperative visual acuity; however, 75% noticed glare and halos at night.

CONCLUSIONS

Laser in situ keratomileusis correction of very high myopia did not cause keratectasia in the long term provided the corneal thickness was respected. A flap thickness setting of 130 microm with a first-generation microkeratome resulted in a high number of cut failures. Most patients were happy with the results despite a modest level of accuracy and glare.

Topical allopurinol or corticosteroids and acetylcysteine in the early treatment of experimental corneal alkali burns: a pilot study

PURPOSE

To investigate the effect of topical allopurinol on experimental corneal burns and to compare this to established treatment modalities such as topical prednisolone and acetylcysteine.

METHODS

Twenty Wistar rats were randomly assigned to four groups (n=5 each). The groups were controls (normal saline), allopurinol 0.4% eye drops, prednisolone acetate 1% eye drops and acetylcysteine 8% eyedrops. Corneal burn was induced using a 3 mm paper disc soaked in 1N NaOH for 60 seconds. Drops were instilled 6 times per day. In addition, one drop/day ofloxacine was given to prevent secondary infections. Eyes were enucleated 50 hours later and fixed in 4.5% formaldehyde. Three histological levels of each globe were stained with hematoxylin-eosin and examined by two independent masked investigators using a 0 to 4+ inflammatory score. All pair-wise multiple comparison procedures (Student-Newman-Keuls method) were applied for statistical work-up.

RESULTS

All three substances significantly reduced the number of histologically visible inflammatory cells compared to the control group (p<0.05).

CONCLUSIONS

In the present study, topical allopurinol was as effective as established drugs, namely steroids and acetylcysteine, in the early treatment of experimental alkali corneal burns.

Differences in the composition of inflammatory cell infiltrate in lens-induced uveitis under therapy with allopurinol or steroids

PURPOSE

The aim of this study was to compare the qualitative changes in the composition of inflammatory cell infiltrate in lens-induced uveitis (LIU) under treatment with allopurinol (Allo), methylprednisolone (Pred) or the two drugs combined (Allo/Pred).

METHODS

Twenty male Wistar rats were sensitized with lens proteins for eight weeks. Intravenous (IV) therapy was started after anterior capsule disruption in one eye of each animal. Five rats were randomly assigned to each of the four groups: controls, Allo (50 mg/kg bw), Pred (7.5 mg/kg bw) and Allo/Pred (50 mg/7.5 mg per kg bw). Eyes were enucleated 24 hours later and fixed in paraformaldehyde/glutaraldehyde. Sections at three levels were stained with Giemsa and examined using a 0 to 4+ score for each type of inflammatory cell. Granulocytes were seen as neutrophils and eosinophils. Neutrophils were divided into polymorphs and "others", and graded with lymphocytes.

RESULTS

In all therapy groups there was a significant reduction of polymorphs (p<0.05) in comparison to the control group. There was also a significant reduction in lymphocytes (p<0.05) in the Pred and Allo/Pred groups as compared to the control group and the Allo group.

CONCLUSIONS

Single-dose IV allopurinol significantly reduced the overall number of polymorphonuclear leucocytes in LIU. Unlike methylprednisolone, allopurinol did not have any significant impact on lymphocytes.

[Histopathology of 8 corneal buttons after penetrating keratoplasty in silicone oil-associated keratopathy]

BACKGROUND

In the literature there is only a limited number of morphological reports on clinically diagnosed silicone oil associated keratopathy describing different histological changes. The purpose of the present study was to evaluate the most common histopathological features of this disorder.

MATERIAL AND METHODS

We reviewed the registry of the ophthalmopathological laboratory at the University of Marburg with respect to the following histopathological diagnoses: "bullous keratopathy", "endothelial-epithelial corneal decompensation", "band keratopathy" and "endothelial degeneration". These specimens were cross-checked with appropriate medical records. Eight specimens with a clinical diagnosis of silicone oil induced keratopathy were identified. All specimens were examined by light microscopy.

RESULTS

Histologically, a long-standing bullous keratopathy was seen in 5 out of 8 specimens. A descemetocele was present in two other corneas. One case displayed band keratopathy. A posterior collagenous layer (PCL) between Descemet's membrane and the endothelium was identified in 7 out of 8 specimens examined. This layer was of a fibrillar type in 2 corneal buttons and of a fibrocellular type in all remaining specimens with PCL. PCL was associated with endothelial cell loss and degeneration. The endothelial cell density varied between 0 and 5 cells per high power field.

CONCLUSION

Posterior collagenous layer associated with degenerating endothelium appears to be the most frequent histopathological feature in silicone oil induced keratopathy. The variety of PCL in this condition makes a firm histopathological diagnosis of "Silicone oil induced keratopathy" rather difficult.

Surgical Treatment of Keratoconus at the Turn of the 20th Century

PURPOSE

This paper reviews surgical modalities for treatment of keratoconus at the threshold of the 20th century.

METHODS

All ophthalmic literature from 1895 until 1925 in English and German, available at the library of the Institute of Ophthalmology, London, United Kingdom, was studied with respect to this topic.

RESULTS

Three thermal procedures were described; galvanocauterization with perforation, without perforation, and a non-contact application of heat to the corneal apex. Radial extension of a thermal burn to correct the minus cylinder represented a further modification. Excision of the conical area was suggested either as a lamellar dissection or as a full thickness trephination. Incision of the cone appeared to be less popular. In staged procedures, a combination of galvanocauterization, splitting of the cornea, conjunctival flap, and a subsequent optical iridectomy were applied.

CONCLUSION

The treatment of keratoconus 100 years ago used refractive surgery to improve visual function by modifying corneal shape.

[Immunological effect of systemically administered allopurinol in experimental autoimmune uveitis]

PURPOSE

Allopurinol shows beneficial effects in the systemic treatment of lens-induced uveitis. This is believed to be due to the reduction of oxidative tissue damage via a dose-dependent free radical scavenging ability and an immunomodulating effect. The purpose of this study was to investigate the immunological effects in experimental autoimmune uveitis after systemic treatment with allopurinol (AL) and steroids (STER).

METHODS

31 male Lewis rats were immunized with crude retinal extract, Freund's Adjuvans and pertussis toxin. The rats were divided into four groups: healthy rats (BASIS, n = 3), experimental autoimmune-uveitis without therapy (EAU, n = 9), 50 mg/kg bw. allopurinol i.v. (ALSYS, n = 9), and 7.5 mg/kg bw. methylprednisolone i.v. (STSYS, n = 10). ALSYS and STSYS received five intravenous injections during the 2 weeks immunization period. The rats' sera were tested against Western Blots (WB) of electrophoretic separations of retinal proteins. Based on digital image analysis, an analysis of discriminance was performed.

RESULTS

The multivariate analysis of discriminance revealed a significance difference between the WBs of ALSYS and STSYS (p < 0.01) compared to EAU without therapy. The number and intensity of peaks in WBs were strongly reduced in the ALSYS group compared to EAU.

CONCLUSION

AL revealed a strong immunomodulating effect in the treatment of experimental autoimmune uveitis that is markedly stronger than that of steroids. Together with the antioxidative effect of allopurinol known from previous studies, this drug could be a new promising therapeutic approach in the treatment of uveitis.

Induced corneal astigmatism using an asymmetric corneoscleral tunnel and a large-optic intraocular lens

PURPOSE

To prospectively evaluate the induction of corneal astigmatism using an asymmetric corneoscleral tunnel incision (J-incision) to implant large-optic (7.0 mm) intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, University of Bonn, Germany.

METHODS

Thirty-five patients had sutureless phacoemulsification with implantation of a 7.0 mm poly(methyl methacrylate) posterior chamber IOL using an inverse J-shaped asymmetric tunnel incision. The corneal astigmatism was measured by corneal keratometry and topography preoperatively and 1 day and 1 and 3 months postoperatively. Induced astigmatism was calculated by vector analysis.

RESULTS

Mean induced changes in the corneal radii measured by keratometry were 0.17 mm +/- 0.14 (SD) on the first postoperative day, 0.18 +/- 0.14 mm after 1 month, and 0.17 +/- 0.14 mm after 3 months. Mean postoperative induced astigmatism measured by corneal topography was 1.08 +/- 0.66 diopters (D), 0.89 +/- 0.78 D, and 0.85 +/- 0.70 D, respectively. No signs of wound instability were detected.

CONCLUSION

An asymmetric corneoscleral incision was suitable for implantation of large-optic IOLs, resulting in immediate stability of the induced cylindrical power in the central 3.0 mm zone as measured by keratometry. A reduction in induced corneal astigmatism can be achieved using this technique versus using symmetrical wound constructions and large-optic IOLs.

Effects of systemically applied allopurinol and prednisolone on experimental autoimmune uveitis

PURPOSE

To compare the effects of allopurinol to those of prednisolone on the oxidative tissue damage and inflammatory response in experimental autoimmune uveitis (EAU).

METHODS

Experiments were performed using 27 male Lewis rats. EAU was induced by means of crude retina extract, Freund's adjuvant and pertussis toxin. One group of animals served as controls and two groups were treated systemically, one with allopurinol and one with prednisolone. At the end of the experiments lipid peroxides (LPO), myeloperoxidase activity (MPO), and histological changes were determined in the retinal tissue. LPO were measured by two different methods [thiobarbituric acid reactive substances (TBARS) and malondialdehyde-like substances].

RESULTS

Allopurinol led to a significant reduction in LPO and MPO levels. The steroid treatment also resulted in a significant reduction in MPO activity but LPO were significantly reduced only when measured as TBARS. Histological changes were significantly reduced by allopurinol only.

DISCUSSION

Allopurinol is more effective than prednisolone in treating EAU. Its efficacy can be explained by the antioxidative/antiinflammatory and probably immunological action. The antiinflammatory effects of prednisolone are not sufficient to reduce the tissue damage. Allopurinol promises to be a useful alternative to steroids in the treatment of uveitis.