Can Ustundag

Optical coherence tomography for evaluation of anatomical changes in the cornea after laser in situ keratomileusis

Purpose: To examine the use of optical coherence tomography (OCT) in evaluating anatomical changes after laser in situ keratomileusis (LASIK) and complications related to the interface and corneal flap. Setting: Istanbul University Eye Research Center and Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey. Methods: Eleven eyes of 11 patients who had myopic LASIK were included in the study. Mean age of the 7 men and 4 women was 29.4 years ± 6.9 (SD). Cases analyzed included uneventful LASIK (4 eyes), epithelial ingrowth (5 eyes), and flap striae (2 eyes). Corneas were examined by OCT (Humphrey Systems). Results: Optical coherence tomography resolved corneal flap and residual stromal layers in all cases. The mean thickness of the corneal flap and residual stroma was 138.2 ± 16.5 &mgr;m and 321.7 ± 32.1 &mgr;m, respectively. Interface between the corneal flap and residual stroma was shown by OCT. Optical coherence tomography revealed that the eye with flap striae had flap displacement undetected by biomicroscopy. Epithelial ingrowth was shown as a highly reflective area. Conclusion: Optical coherence tomography appears to be a promising method for evaluating anatomical changes in the cornea after LASIK.

Morphologic proof of the toxicity of mitomycin C on the ciliary body in relation to different application methods.

Abstract · Background: Since postoperative hypotony has been a frequent complication of glaucomatous filtration surgery with adjunctive use of mitomycin C (MMC), the question arises of whether there may be another application method which can minimize this side effect. The purpose of this study was to establish the morphologic side effects of different application methods. · Methods: MMC 0.2 mg/ml was applied to the episclera of nine eyes of six pigmental rabbits at random via collagen shield (CS), soft contact lens (CL), or lyophilisate (20 µg; LY) for 5 min. Two eyes (controls) had a subconjunctival injection of BSS only. Another control eye was left untreated (no injection). No trabeculectomy was performed. One hour later the amounts of MMC in the conjunctiva and aqueous were analyzed by reverse-phase high-pressure liquid chromatography. Ciliary bodies were dissected from the enucleated eyes, embedded and investigated by transmission electron microscopy (TEM). Cell height of the nonpigmented ciliary epithelium was morphometrically assessed by means of computer-assisted image analysis. · Results: The light-microscopic analysis of the sectioned cell area revealed reduction of the cell height of the non-pigmented ciliary epithelium (NPCE) after application with soft contact lens (foufold) and collagen shield (2.5-fold) but not with lyophilisate compared to the untreated eye. The following ultrastructural changes were seen: loss of apical microvilli (CS, CL, LY), disintegrating melanin granules within NPCE (CS), lysis of entire areas with NPCE cells (CS), myelin figures within mitochondria (LY), intracellular vacuoles (CS, CL), lysis of myelinated nerves (CS), myelin figures in mitochondria of endothelial cells (LY), and lysis of stromal fibrocytes (CS). In the control eyes (injection of BSS) none of these ultrastructural changes were detected in the cylindrical NPCE cells. The concentration of mitomycin in the aqueous humor after topical application of MMC on the episclera for 5 min were all below the detection limit (<10 ng/ml). The concentration of MMC in the conjunctiva ranged from 2.1 to 3.7 µg/g. · Conclusion: Severe morphologic alterations were seen at the electron-microscopic level after application of MMC 0.2 mg/ml with a collagen shield and with a soft contact lens. They were mildest with lyophilisate and absent in the BSS controls. A new administration device is needed if trabeculectomy is to be performed successfully using MMC in human glaucomatous eyes.

Corneal iron ring associated with iatrogenic keratectasia after myopic laser in situ keratomileusis

A 23-year-old woman had bilateral myopic laser in situ keratomileusis (LASIK). Two months postoperatively, she reported decreased visual acuity. Biomicroscopic examination revealed a corneal epithelial iron ring around the central keratectasia on both corneas. The appearance of the ring pattern was similar to the iron deposits of the Fleischer ring of keratoconus.

Visual field changes after laser in situ keratomileusis in myopic eyes

Purpose: To evaluate the effect of acute elevation of intraocular pressure (IOP) during laser in situ keratomileusis (LASIK) on the visual field in myopic eyes. Setting: Istanbul University, Cerrahpassa Medical Faculty, Istanbul, Turkey. Methods: Thirty‐seven eyes of 37 patients were included in the study. The LASIK procedure was performed using the Hansatome® microkeratome (Bausch & Lomb) and the Summit SVS Apex Plus® 193 nm argon–fluoride excimer laser. Visual field testing was performed twice before LASIK and 1 day and 24 months after LASIK. Seventy‐six points, 6 degrees apart, in the central visual field (Central 30‐2) were tested for threshold sensitivity (Humphrey). The mean threshold sensitivity of baseline and post‐LASIK visual field examinations was calculated in each patient. Seventy‐six points of the Central 30‐2 test were divided into 21 clusters corresponding to perimetric nerve‐fiber bundles derived from Peridata software version 6.2a (Interzaag AG). The mean threshold sensitivity of each cluster and the visual field indices (mean deviation [MD] and corrected pattern standard deviation [CPSD]) in baseline and follow‐up visual fields were compared using analysis of variance. Results: The mean age of the 23 men and 14 women was 31.04 years ± 6.55 (SD). The mean spherical equivalent refraction was −4.21 ± 1.66 diopters (D) (range −2.25 to −6.75 D). The mean duration of suction was 42.29 ± 29.06 seconds. The mean visual field sensitivity at baseline and the 2 follow‐up examinations was 25.97 ± 2.04 dB, 25.70 ± 1.99 dB, and 27.17 ± 1.68 dB, respectively (P = .181). There was no difference between preoperative and postoperative visual field clusters except in area 13. In area 13, threshold sensitivity was decreased at 1 day (P = .039) and at the preoperative level at 24 months. The MD of the visual fields was −3.53 ± 1.67 dB, −3.61 ± 2.91 dB, and −2.61 ± 1.66 dB at the preoperative and 2 postoperative examinations, respectively (P = .495). The mean CPSD of the visual fields was 1.76 ± 1.24 dB, 1.42 ± 0.85 dB, and 1.74 ± 0.86 dB, respectively (P = .680). Conclusion: Laser in situ keratomileusis did not cause visual field defects in mild to moderate myopic patients who had no risk factors that might render the optic nerve more vulnerable to damage.

Long term follow-up of retinal nerve fiber layer thickness in eyes with optic nerve head drusen

Purpose. To investigate the effect of optic nerve head drusen (ONHD) on the retinal nerve fiber layer (RNFL) thickness during follow-up period. Methods. Twenty-three non-glaucomatous eyes having clinically visible ONHD confirmed by colored disc photos were studied. RNFL thickness was determined with Optical Coherence Tomography (OCT). Eyes were re-examined after average of 18 months (ranging between 14 and 22 months). Mean RNFL thickness of each quadrant was compared with previous results at each follow-up visit. Results. Mean RNFL thickness was 88.43 ± 10.2 micron at first visit and 90.35 ± 6.9 micron at follow-up in eyes with clinically visible ONHD. The difference between the mean RNFL thickness measured from inferior, superior, nasal and temporal quadrant at first and follow-up visits was not significant (paired t -test, p > 0.05). Conclusion. The presence of drusen was found to have no effect on RNFL thickness at follow-up visits. OCT may provide a useful means to evaluate and follow up the RNFL thickness in these patients.

Repair of Descemet’s membrane detachment after viscocanalostomy

We report an alternative descemetopexy technique in a case of Descemets membrane detachment after viscocanalostomy, possibly caused by high-molecular-weight viscoelastic material.

Effect of mitomycin C on aqueous humor flow, flare and intraocular pressure in eyes with glaucoma 2 years after trabeculectomy

Abstract · Background: The purpose of this study was to determine the intraocular pressure (IOP), aqueous humor flow, flare and ocular side effects in eyes with a history of hypotony after trabeculectomy with adjunctive mitomycin C (MMC). · Methods: Thirty-six eyes with primary or secondary open-angle glaucoma and IOP ≤8 mmHg during the postoperative period were studied 745±315 days after surgery. MMC (0.2 or 0.5 mg/ml) was applied to the episclera with a cellular sponge. Flare was studied with the Kowa Laser Flare Meter 500. Aqueous humor flow was measured in the afternoon (Fluorotron Master II). IOP, visual fields and best corrected visual acuity were also examined. Twenty-two contralateral eyes without surgical intervention served as controls. · Results: The mean age of patients was 44.5±16.8 years. The mean IOP was significantly lower in the MMC group than in the control group: 9.6±6.4 mmHg vs 18.0±13.6 mmHg at 2 years (P<0.001). Aqueous flow was significantly lower in subjects treated with MMC than in controls (P<0.001). The flare values were significantly higher in the MMC-treated group, with a mean of 12.0±7.7 photon counts/ms, than in the control group, mean 7.9±4.6 photon counts/ms (P<0.019). · Conclusion: Our data suggest that MMC is a useful ocular hypotensive agent which seems to participate in a change in aqueous humor dynamics when applied topically as an aqueous solution.

Scleral Tunnel for the Implantation of Glaucoma Seton Devices

The technique described in this paper shows how to use a long scleral tunnel for the implantation of anterior tube parts of glaucoma drainage devices. It involves the creation of a scleral tunnel beginning 10 mm behind the limbus and extending to the anterior chamber. Anterior tube parts of Krupin eye valve with disk is inserted through the scleral tunnel to the anterior chamber. The disk part is secured to the episclera as used in the standard technique. We have used this technique in 6 eyes of 6 consecutive patients with refractory glaucoma. The placement of anterior tubes as part of glaucoma seton devices was done in all patients. While mean intraocular pressure (IOP) was 39.3 +/- 4.9 mm Hg (ranged from 29 to 56 mm Hg) preoperatively, it was 16.6 +/- 5.3 mm Hg (ranging from 11 to 25 mm Hg) at the end of follow up. Mean follow-up time was 7.16 +/- 1.16 months (ranging from 6 to 9 months). After surgery, conjunctival erosion or displacement of the anterior tube and dellen formation were not found in any eyes. The use of a long scleral tunnel for the implantation of anterior tube parts of glaucoma seton devices offers some advantages over standard implantation techniques.

Fungal keratitis after nonpenetrating glaucoma surgery

Purpose. The purpose was to report a case of fungal keratitis that occurred following viscocanalostomy. Methods. A 63-year-old man who underwent viscocanalostomy in his left eye presented with pain, redness, watering, and a decrease in visual acuity. Slit lamp examination showed teardrop-like stromal infiltration of the superior cornea. Corneal and conjunctival scrapings were obtained and a corneal biopsy was performed. Results. Microscopic examination of smears demonstrated no bacteria and fungi. Corneal biopsy revealed dichotomously branching, septate hyphae suggestive of Aspergillus species. Culture identified no microorganism. The patient responded to amphotericin B treatment and the corneal infiltration resolved, leaving a plaquelike corneal scar. Conclusion. Fungal keratitis may occur after viscocanalostomy, but prompt diagnosis and treatment can preserve the eye.

Efficacy of argon laser trabeculoplasty: 3-year preliminary results of a prospective placebo-controlled study

Abstract• Background: It was the purpose of this study to evaluate the efficacy of argon laser trabeculoplasty (ALT) in controlling intraocular pressure (IOP) and avoiding surgical intervention. We also investigated whether topically applied diclofenac sodium eye drops had an influence on the success rate of ALT compared with placebo eye drops. • Methods: The indication for ALT was progressive glaucoma uncontrolled by maximal tolerated medical therapy. Thirty-nine of 41 patients were available for follow-up after 1122±239 days. • Results: Twenty-one of 39 eyes failed during the first 3 years of follow-up for one or more reasons: 11 eyes required additional laser treatment and/or filtration surgery because of progressive visual field loss or unacceptably high IOP, 9 eyes failed to have a final IOP ≥21 mmHg, and 7 eyes failed because of an increase in the number of the medications. This yields a success rate for ALT of 46% for 3-year follow-up. There was no significant difference between diclofenac sodium- and placebotreated eyes concerning the success rate after 3 years (P>0.05). • Conclusion: We conclude that the use of ALT for the treatment of glaucoma is best reserved for cases in which medical avenues of treatment have been exhausted.