Rengin Yildirim

Reproducibility of corneal flap thickness in laser in situ keratomileusis using the Hansatome microkeratome

Purpose: To evaluate the reproducibility of flap thickness during laser in situ keratomileusis (LASIK) and to analyze the effect of preoperative central corneal thickness and corneal keratometric power on flap thickness. Setting: Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey. Methods: One hundred forty eyes with a mean preoperative pachymetry of 554.4 &mgr;m ± 36.3 (SD) and a mean keratometry of 43.5 ± 1.9 diopters had LASIK using the Hansatome automated microkeratome (Bausch & Lomb Surgical) and a 193 nm argon–fluoride excimer laser (Summit SVS Apex Plus). The 180 &mgr;m microkeratome plate was used in all procedures. Corneal thickness was measured with an ultrasonic pachymeter (Advent, Mentor O&O Inc.) before and during the flap procedure, and the difference was taken as flap thickness. The data were analyzed using a 1‐tailed t test and Pearson correlation coefficient. Results: The mean flap thickness was 120.8 ± 26.3 &mgr;m. There was a low correlation between baseline central corneal thickness and corneal flap thickness (P = .6, r = 0.046). There was no correlation between preoperative keratometry and flap thickness (P = .01, r = 0.203). Conclusions: The Hansatome microkeratome does not always produce a corneal flap of the intended thickness. Factors other than keratometry and pachymetry must affect flap thickness.

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.

Silicone oil removal using a self-sealing corneal incision under topical anesthesia.

BACKGROUND AND OBJECTIVE To report the results of silicone oil removal from aphakic eyes using a self-sealing clear corneal incision under topical anesthesia. PATIENTS AND METHODS Twenty-two eyes of 22 patients who had pars plana vitrectomy combined with silicone oil injection underwent silicone oil removal under topical anesthesia using a self-sealing clear corneal incision. Mean time between silicone oil injection and removal was 3.1+/-1.42 months. Fourteen eyes were filled with 1300 cs of silicone oil and 8 eyes were filled with 5700 cs of silicone oil. The removal was performed with passive washout in the eyes filled with 1300 cs of silicone oil and with active aspiration in the eyes filled with 5700 cs of silicone oil. RESULTS All of the 22 silicone oil removal procedures performed under topical anesthesia had clear corneal incisions that did not require suturing at the end of surgery. Three cases that had 1300 cs of silicone oil required aspiration because of residual silicone oil bubbles. CONCLUSION Silicone oil can be removed from the aphakic eye using a self-sealing corneal tunnel incision under topical anesthesia.

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.

Exodeviation following monocular myopic regression after laser in situ keratomileusis

We report a 44-year-old woman with intermittent left exotropia of 35 prism diopters at distance who initially exhibited alignment of both eyes after bilateral laser in situ keratomileusis (LASIK). The exophoria was not preserved due to myopic regression in the dominant eye. An uneventful LASIK treatment was performed to correct -11.00 -0.50 x 130 in the right eye and -13.50 -1.50 x 145 in the left eye. The aim was to achieve emmetropia in both eyes. Although an examination revealed exophoria at near and distance during the 6 months following refractive surgery, the tropic aspect of the divergent deviation appeared in the right eye following the myopic regression. Laser in situ keratomileusis is an effective option to achieve binocular visual quality in myopic anisometropic patients. However, myopic regression after LASIK may disrupt the binocular visual quality.

Comparison of retinal nerve fiber layer and macular thickness measurements with Stratus OCT and OPKO/OTI OCT devices in healthy subjects

AIM To compare retinal nerve fiber layer (RNFL) and macular thickness measurements obtained with the Stratus optical coherence tomography (OCT) and OPKO/OTI OCT devices. METHODS Included in the study were 59 eyes of 30 participants. All measurements for each eye were done on the same day with both devices. Students paired t-tests were used to compare the central macular thickness and RNFL measurements of the Stratus OCT and OPKO/OTI OCT. Pearson correlation was used to assess the relationship between the devices. Coefficient of variation (COV) was calculated to assess intersession repeatability. RESULTS Using both the Stratus OCT and OPKO/OTI OCT, respectively, the measured mean average RNFL thicknesses were 98.9±11.1 µm and 115.1±9.6 µm (P=0.001), and the measured mean central retinal thicknesses (CRT) were 196.2±18.8 µm and 204.5±21.1 µm (P<0.001). Measured by the two devices, the RNFL thickness values were correlated in all quadrants, as were the retinal thickness values except the inferior outer sector. COV for average RNFL and CRT thickness were 2.9% and 4.6% for Stratus OCT, and 2.1% and 4.2% for OPKO/OTI OCT, respectively. CONCLUSION We found good reproducibility of RNFL and retina thickness measurements for both Stratus OCT and OPKO/OTI OCT devices. However, even though the two OCT systems provided statistically correlated results, the values for both RNFL and macular thickness were statistically different. RNFL and macular thickness measurements with the OPKO/OTI OCT were higher than that of the Stratus OCT; therefore, the two OCT systems cannot be used interchangeably for the measurements of RNFL and macular thickness.

Corneal Viscoelastic Properties in Patients with Angioid Streaks

Abstract Purpose: The aim of this study is to investigate the possible corneal biomechanical changes in patients with angioid streaks and to understand if the calcified and thickened Bruchs membrane associated with angioid streaks influences elasticity of the eye and intraocular pressure. Materials and Methods: Twelve eyes of 12 patients with angioid streaks (six males and six females) and 12 eyes of 12 age- and sex-matched healthy volunteers were enrolled in the study. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were measured with an Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured with an ultrasound pachymeter. Results: Mean CRF and IOPg values in eyes with angioid streaks (12.10 ± 1.27 and 17.76 ± 2.73, respectively) were significantly higher than those in matched control eyes (10.70 ± 1.28 and 14.67 ± 2.72, respectively; p = 0.01 for CRF, p = 0.007 for IOPg). There was no statistically significant difference between eyes with angioid streaks and matched control eyes in measured CH, IOPcc and CCT values (p = 0.29, p = 0.09 and p = 0.86, respectively). Conclusions: This study revealed that angioid streaks can affect corneal biomechanical properties by increasing CRF, as compared to the healthy eyes. Increased CRF means increased resistance for effect of IOP on eye so it can be speculated that these patients tend to be more protected for glaucoma.

Effect of Hemifacial Spasm on Intraocular Pressure Measurement

Purpose To evaluate the effect of hemifacial spasm (HFS) on intraocular pressure (IOP) measurement. Methods Twenty-four consecutive patients with HFS and 25 age- and gender-matched randomly selected eyes of healthy volunteers underwent corneal pachymetry and IOP measurements using Goldmann applanation tonometer (GAT) and noncontact tonometer (NCT). IOP measurements were performed before (during HFS) and 2 weeks after Botox injections in HFS patients and in healthy volunteers without Botox injections. Results There was no statistical difference between involved eye side and uninvolved eye side of HFS patients in measured central corneal thickness. Similarly, no difference was found between involved eye side of HFS patients and controls. There were no statistically significant differences comparing IOP values before treatment and levels measured at 2 weeks of Botox injections, either with GAT (p = 0.33, 0.11) or NCT (p = 0.80, 0.43) devices in the involved eyes and uninvolved eyes of patients with HFS, respectively. There were also no significant differences in these parameters (GAT (p = 0.63) and NCT (p = 0.54)) in controls. Conclusions Contractions in facial muscles may not lead to significant increase in IOP in HFS patients. This result may help clinical decision making in the treatment of glaucoma patients with HFS. This trial is registered with NCT03390803.

Eye Injuries from Pencil Lead: Three Cases

Corneal stromal and/or penetrating ocular injuries from pencils and pencil lead are more common in childhood and may lead to intraocular infection or severe intraocular sterile inflammatory reaction. Herein we report 3 children with ocular trauma due to pencil lead injuries. The first case had corneal stromal injury caused by a pencil. In the second case, a pencil perforated the cornea and contacted the iris. In the third case, pencil lead perforated both the cornea and iris and reached the vitreous through the lens zonules. Intracameral triamcinolone (2 mg/0.05 mL) was injected after the pencil lead was removed from the eyeball. Topical anti-inflammatory and cycloplegic drops were prescribed. In conclusion, corneal and especially penetrating ocular injuries from pencil lead may have a good prognosis with the use of appropriate anti-inflammatory and prophylactic antibiotic treatment and follow-up.