Cengiz Aras

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.

In vitro antimicrobial activity of silicone oil against endophthalmitis-causing agents.

PURPOSE To investigate the antimicrobial activity of silicone oil against endophthalmitis-causing agents in vitro. METHODS The antimicrobial activity of silicone oil was tested on Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Candida albicans, and Aspergillus spp. The bacteria and fungi were separately inoculated into 1,300 centistokes silicone oil. Control inoculations were done in two different media: physiologic saline and brain-heart infusion (BHI) for bacteria and Sabouraud broth and physiologic saline for fungi. From each medium, 0.001-mL samples were taken and plated in Petri dishes. After overnight incubation, colony-forming units (CFUs) were enumerated. Culturing from the initially prepared specimens, incubating overnight, and counting CFUs was repeated until no growth of microorganisms was seen in the silicone oil-containing media. Macroscopic photography of the colonies and light microscopic photography of microorganisms were performed. RESULTS All the microorganisms showed an apparent decrease in CFUs, with elimination between 7 and 21 days in silicone oil. Colony-forming units of microorganisms remained stable in physiologic saline during the study, with the exception of gradual decrease in CFUs of S. aureus and S. epidermidis from the beginning of the third day. In BHI and Sabouraud broth, both bacteria and fungi showed a growth pattern that was compatible with the growth curve of microorganisms. CONCLUSION Silicone oil has an antimicrobial activity against S. aureus, S. epidermidis, P. aeruginosa, C. albicans, and Aspergillus spp., which are common endophthalmitis-causing agents.

Suprachoroidal Seton Implantation in Refractory Glaucoma: A Novel Surgical Technique

PURPOSE To describe a new surgical technique in which aqueous humor is diverted from the anterior chamber to the suprachoroidal space for the augmentation of uveoscleral outflow in the management of refractory glaucoma. METHODS Four painful-blind eyes of four consecutive patients were included in the study. Mean age of patients was 54.7+/- 9.2 years. Preoperative diagnosis was neovascular glaucoma complicating diabetic retinopathy in three cases and chronic angle-closure glaucoma in one case. Mean preoperative intraocular pressure of the patients receiving two medications was 58.5 +/- 9.2 mm Hg. A modified Krupin eye valve with disk was implanted into the suprachoroidal space. The anterior tube part of the Seton device was placed into the anterior chamber through the long scleral tunnel for draining the aqueous humor from the anterior chamber to the suprachoroidal space. RESULTS The placement of modified Krupin eye valve with disk to the suprachoroidal space was achieved in all cases. While mean preoperative intraocular pressure was 58.5 +/- 9.2 mm Hg, it was 14.2 +/- 4.7 mm Hg at postoperative one week. It was 13.5 +/- 4.6 mm Hg and 15 +/- 4.9 mm Hg at one and three months respectively. At the last follow-up visit, mean intraocular pressure was 17.25 +/- 5.37 mm Hg ranging from 12 to 24 mm Hg. Choroidal detachment was developed in one case and regressed in six weeks. Rubeosis irides regressed at third month in three cases. None of the eyes developed suprachoroidal hemorrhage, retinal detachment, or phthisis bulbi. CONCLUSION The drainage of aqueous humor from the anterior chamber to the suprachoroidal space with the implantation of the glaucoma Seton device is effective in lowering intraocular pressure in refractory glaucoma.

Retinal detachment following laser in situ keratomileusis

OBJECTIVE To report the clinical characteristics, surgical management and outcome of retinal detachment following laser in situ keratomileusis (LASIK) in myopic patients. PATIENTS AND METHODS Retrospective review of 10 eyes of 10 myopic patients with retinal detachment who had previously undergone LASIK surgery were analyzed. Included in the study were 7 males and 3 females, aged 22 to 68 years (35.2+/-2.8). RESULTS Mean spherical equivalent refraction was -10.51+/-3.90 D (ranging from -6.37 D to -17.00 D) before surgery. The time interval between the LASIK procedure and the development of retinal detachment varied from two months to nine months (5.2 +/- 2.78 months). The number of retinal breaks was one in 7 patients, two in 2 patients and three in 1 patient. The type of retinal breaks included 7 patients with horse shoe tears, 1 patient with a retinal hole, 1 patient with a giant retinal tear, and 1 patient with retinal dialysis. Retinal breaks were located anterior to the equator in 9 patients and posterior to the equator in 1 patient. Retinal reattachment was achieved with one operation in 8 eyes (80%) and the remaining 2 eyes required a second surgery for the reattachment of the retina. CONCLUSION This study suggests the possible association between retinal detachment and LASIK procedure in patients with myopia. Clinicians should be aware of retinal pathology predisposing to retinal detachment in patients undergoing LASIK.

Decreased tear secretion after laser in situ keratomileusis for high myopia.

PURPOSE To investigate the changes in tear secretion and tear film stability after excimer laser in situ keratomileusis (LASIK) for high myopia. METHODS One eye of 28 patients underwent unilateral LASIK for the correction of myopia with spherical equivalent refractions ranging from -6.37 to -18.25 D (mean, -11.98 +/- 3.45 D). Schirmer tear test values without anesthesia at 5 minutes and tear break-up time values were measured 4 weeks after LASIK. Unoperated contralateral eyes were used as a control for each patient. The Schirmer tear test and tear break-up time values were analyzed statistically using the independent t-test. RESULTS The mean Schirmer tear test value was 16.17 +/- 2.50 mm in the operated eyes and 21.07 +/- 7.03 mm in the unoperated (control) eyes of the same patients (P = .001). The mean tear break-up time value was 21.0 +/- 3.55 seconds in the operated eyes and 21.27 +/- 6.79 seconds in the control eyes (P = .85). CONCLUSION Tear secretion decreased following LASIK probably due to decrease in corneal sensitivity, but tear film stability appeared unaltered.

CHANGES IN TEAR FLOW AND TEAR FILM STABILITY AFTER PHOTOREFRACTIVE KERATECTOMY

PURPOSE To investigate the changes in tear flow and tear film stability after photorefractive keratectomy (PRK) for myopia. MATERIAL AND METHOD One eye of 32 patients underwent unilateral PRK procedure for the correction of myopia ranging from -1.50 to -6.00 diopters (D) (mean -3.65 +/- 1.55 D). Schirmer test values and break-up time (BUT) scores were measured 6 weeks after the PRK procedure. Unoperated, contralateral eyes were used as control eyes for each patient. The Schirmer test scores and BUT values were statistically analyzed using independent t test. RESULTS The mean Schirmer test value was 14.45 +/- 7.79 mm in the operated eyes. It was 28.83 +/- 5.89 in the control eyes. The decrease in Schirmer test value was statistically significant (t = 8.28, p = 0.0001). The mean BUT scores were 13.19 +/- 5.09 s in the operated eyes and 27.83 +/- 9.31 s in the control eyes. The decrease was statistically significant (t = 7.86, p = 0.0001). CONCLUSION PRK causes a decrease in tear flow and tear film stability that is probably caused by decreased corneal sensation after PRK.

Corneal interface abscess after excimer laser in situ keratomileusis

Laser in situ keratomileusis (LASIK) carries the risk of infection. We report a case culture-negative interface abscess following LASIK that was successfully treated with antibiotics and povidone iodine.

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.

Scleral Buckling with a Non-Contact Wide-Angle Viewing System

Purpose: To assess the outcome of scleral buckling surgery using a non-contact wide-angle viewing system for fundus visualization in patients with rhegmatogenous retinal detachment without proliferative vitreoretinopathy. Patients and Methods: Sixteen eyes of 16 patients underwent scleral buckling using a non-contact wide-angle viewing system combined with a 25-gauge illumination fibre inserted into the sclera at the pars plana. Results: The mean age of the patients was 53.6 ± 13.7 years and the mean follow-up time was 13.4 ± 2.8 months. Retinal reattachment was achieved in 13 of the 16 eyes (81%). Three eyes underwent vitrectomy with silicone oil injection because of development of proliferative vitreoretinopathy in 2 eyes and scleral perforation due to excessive indentation during cryoretinopexy in 1 eye. Two eyes developed limited subretinal haemorrhage during subretinal fluid drainage. Conclusion: Simultaneous use of a non-contact wide-angle viewing system combined with a 25-gauge light fibre illumination for fundus visualization brings the advantages of microsurgery and indirect ophthalmoscopy into scleral buckling surgery.