Browsing by Author "Demirok, A"

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Changes in Anterior Chamber Depth and Axial Length Measurements After Radial Keratotomy
(Royal Coll Ophthalmologists, 1999) Demirok, A; Çinal, A; Simsek, S; Vasar, T; Bayram, A; Yilmaz, OF
Purpose To evaluate the changes that occur in anterior chamber depth and globe axial length after radial keratotomy (RK) surgery in cases with different degrees of myopia. Methods One hundred and twelve eyes that underwent RK were studied. The eyes were divided into two groups: 70 eyes with a correction of myopia of 4.00 D and under after RK (group 1) and 42 eyes with a correction of myopia of more than 4.00 D (group 2). Routine examinations were done in all cases. Ultrasonic biometry and central anterior chamber depth and axial length were measured pre-operatively and on the third day, second week, third month and sixth month post-operatively. Results Pre-operatively the average globe axial length was longer in group 2 than group 1. When all post-operative measurements were compared with pre-operative measurements in group 1, there was a decrease in anterior chamber depth and globe axial length, but no significant difference was found except on the third day (t = 3.15, p = 0.003). In group 2 there was an insignificant decrease in axial length but the decrease in anterior chamber depth was significant at all measurement times except for the sixth month. Conclusions Refractive changes related to biometric changes after RK are not important compared with the total refractive corrections of RK. These changes should be considered, however, when planning RK procedures.
A Comparative Study on the Effect of Radial Keratotomy in Patients Who Live at Sea Level and High Altitude
(Royal Coll Ophthalmologists, 1999) Çinal, A; Yasar, T; Demirok, A; Simsek, S; Yilmaz, ÖF
Purpose To compare the refractive and keratometric results of matched pairs of patients who underwent radial keratotomy (RK) at sea level and high altitude. Methods The results of 30 eyes that underwent RK procedures in two clinical centres at different altitude were analysed. One centre was at sea level (Istanbul) and the other at an altitude of 1720 m (Van). The patients in the two centres were matched regarding gender, age, degree of myopia, number of incisions and optic zone size. There were 15 eyes in each group. All operations were performed with a diamond blade using a Russian technique by the same surgeon. Results The mean pre-operative spherical equivalent cycloplegic refractions (SECR) were -6.33 +/- 1.15 D and -6.32 +/- 1.01 D in the Istanbul and Van groups, respectively (p = 0.96). The mean post-operative SECRs were -1.93 +/- 1.03 D and -0.28 +/- 0.57 D in the Istanbul and Van groups, respectively (p < 0.001). The mean SECR changes were 4.40 +/- 0.92 D and 6.03 +/- 1.13 D in subjects who had undergone RK at sea level and at 1720 m, respectively (p < 0.001). Conclusion These results show that a higher myopic correction can be provided in patients who undergo RK at high altitude compared with those operated on at sea level. The RK nomograms used by refractive surgeons performing RK surgery at high altitude may need to be redesigned in the light of future studies with long-term follow-up.
The Effect of 0.25% Apraclonidine in Preventing Intraocular Pressure Elevation After Nd:yag Laser Posterior Capsulotomy
(Wichtig Editore, 1998) Simsek, S; Ertürk, H; Demirok, A; Cinal, A; Yasar, T; Karadenizli, G
Purpose. The efficacy and adverse effects of 0.25% apraclonidine on intraocular pressure (IOP) after Nd: YAG laser posterior capsulotomy were investigated, and the results were compared with placebo, 0.50% timolol maleate and 1% apraclonidine. Methods. Eighty eyes were randomly assigned to four groups of 20 eyes. In a double-masked design, the groups were treated with placebo (group I), 0.50% timolol maleate (group 2), 1% apraclonidine (group 3), 0.25% apraclonidine (group 4) one hour before and five minutes after Nd:YAG laser posterior capsulotomy. IOP was measured by applanation tonometry I hour before (baseline IOP) and 1, 3, 24 hours after capsulotomy. Results. The average baseline IOP increased respectively 3.90 +/- 5.35, 5.95 +/- 5.32, 1.15 +/- 3.20 mmHg in the first group 1, 3 and 24 hours post-treatment. There were significant differences between baseline IOP and 1 and 3 hours but not at 24 hours (p=0.004, p=0.001, p=0.13). IOP increased 0.40 +/- 4.08, 0.75 +/- 5.33, 0.80 +/- 6.03 mmHg in the second group at the same times. The differences between the average baseline IOP and the 1, 3 and 24 h measurement were not significant (p=0.83, p=0.65, p=0.93). In the third group, IOP decreased 3.70 +/- 2.40, 3.30 +/- 2.47, 2.65 +/- 1.56 mmHg at the measurement times, with significant differences between the average baseline IOP and the 1, 3 and 24 hour measurements (p=0.001, p=0.0001, p=0.01). In the fourth group IOP increased 0.35 +/- 3.32 mmHg at 1 hour, but decreased 1.25 +/- 3.41, 0.90 +/- 2. 07 mmHg at 3 and 24 hours. The differences were not significant (p = 0.94, p = 0.16, p = 0.08). When the 0.25% and 1% apraclonidine groups were compared, there were significant differences between the average IOP at 1 hour in both groups but not at 3 and 24 hours (p=0.01, p = 0.17, p = 0.21). Similarly, there were no significant differences between the average IOP at the same times when the 0.25% apraclonidine group was compared with the timolol group (p = 0.30, p = 0.08, p = 0.16). Some systemic and local side effects were seen in the timolol and 1% apraclonidine groups, but none with 0.25% apraclonidine. Conclusions. It was concluded that 0.25% apraclonidine is effective in preventing the early elevation of IOP after Nd:YAG laser posterior capsulotomy and may offer an alternative to 0.50% timolol maleate and 1% apraclonidine.
The Effect of Altitude on Radial Keratotomy
(Elsevier Science inc, 1998) Simsek, S; Demirok, A; Cinal, A; Yasar, T; Yilmaz, OF
The authors analyzed refractive results of patients who underwent radial keratotomy (RK) at sea level and high altitude and evaluated the effects of the altitude. A total of 102 eyes undergoing RK procedures performed in two clinical centers having different altitude were analyzed. The results compared between subjects who had undergone RK at sea level (Istanbul/Turkey) and at an altitude of 5750 feet (Van/Turkey) were compared. Subjects were 19-42 years old with myopia from -4.00 to -12.00 diopters (D). The average preoperative spherical equivalent cycloplegic refractions (SECR) were -8.01 +/- 1.86 D and -6.99 +/- 2.15 D in the istanbul and Van groups, respectively. These were divided into subgroups according to myopia degree and number of incisions and optic zone size. The RK procedures were performed by the same surgeon with diamond blade in standard Russian style. The average changes in SECR were 5.09 +/- 1.29 D and 6.50 +/- 2.24 D in subjects who had undergone RK at sea level and at 5750 feet, respectively. There was a significant difference between the subgroups (P < 0.0002). This difference was especially higher in the high myopia subgroups. Additionally, we obtained a partial relation between increase of RK incision number and SECR change at high altitude but not at sea level. No notable regression and progression were seen in the 3 months of follow up at high altitude. These results support hy potheses suggesting both corneal hypoxic expansion in the area of RK incisions, which may lead to central corneal flattening, and barometric pressure directly altering corneal shape, which is responsible for the hyperopic shift induced by altitude. Ophthalmologists performing RK surgery at high altitude had better consider redesigning their RK nomograms in light of these findings. However, when the nomogram used at sea level was used at high altitude, the subjects became hyperopic. (C) 1998 Japanese Ophthalmological Society.
Effect of Infliximab on Refractory Uveitis in Behcet's Disease
(Harvey Whitney Books Co, 2004) Sayarlioglu, M; Cinal, A; Topcu, N; Demirok, A
The Effect of Pterygium Surgery on Corneal Topography
(Slack inc, 2001) Cinal, A; Yasar, T; Demirok, A; Topuz, H
OBJECTIVE: The aim of this prospective randomized clinical study was to evaluate the effect of pterygium surgery on the corneal topography using a computerized corneal topography system. PATIENTS AND METHODS: Computerized corneal topography was performed on 27 patients with primary pterygium before and after pterygium excision surgery. The topographical changes that occurred following surgery were evaluated using paired and unpaired two-tailed t-test and Pearson coefficient of correlation analyses. Simulated keratometric astigmatism at the central 3 mm and the total mean refractive powers of the whole cornea were measured before and after surgery. Following surgery, fattened or steepened corneal areas were determined. RESULTS: Simulated keratometric astigmatism at 3 mm was found to be 2.30 +/- 2.08 D (0.2 - 7.63) preoperatively and 0.82 +/- 0.74 D (0.06 - 2.79) postoperatively. The difference between these two values was statistically significant (t = -3.46, P = 0.002). Total mean refractive power of the whole cornea was found to be 42.26 +/- 0.63 (40.80 - 43.64) preoperatively and 43.69 +/- 0.88 (41.50 - 44.90) postoperatively and the difference was 1.42 +/- 0.87. There was a statistically significant high difference (t = 28.36, P < 0.001). When preoperative and postoperative corneal topographies were compared, the whole cornea was found steeper at the postoperative period except a little region in the superior nasal quadrant. CONCLUSION: We believe that corneal topographical changes caused by the pterygium are almost reversible after surgical treatment, and postoperatively the cornea becomes steeper.
Effect of Sex in Branch Retinal Vein Occlusion
(Wichtig Editore, 1998) Simsek, S; Demirok, A; Çinal, A; Yasar, T
Purpose. To evaluate the effect of sex in relation to crossing numbers, arterial overcrossings and occlusion sites in patients with branch retinal vein occlusion (BRVO). Methods. Fifty-one eyes with BRVO (study group) and 48 eyes with retinal problems other than BRVO (control group) were investigated All venous occlusions were examined in detail with regard to their anatomical positions, sites and arteriovenous crossings on the retinal surrounding area two disc diameters nasally, four disc diameters temporally three disc diameters superiorly and three inferiorly from the optic disc, in the arteriovenous phase of fundus fluorescein angiography and fundus color photography. Results. The study group comprised 29 women (56.86%) and 22 men (43.14%). All occlusions were unilateral and located at the crossing areas. BRVO had arterial overcrossing in 28 eyes (96.6%) in females and 22 eyes (95.5%) in males (p > 0.005). The average numbers of crossings were 7.79 +/- 1.57 in females and 7.82 +/- 1.05 in males in the study group (p > 0.05), and respectively 7.30 +/- 1.19 and 6.95 +/- 1.13 (p > 0.05) in the control group. The average arterial overcrossing ratios were 75% in females and 71% in males in the study group (p > 0.05), and 74% and 65% in the control group (p > 0.05). Conclusions. Our data suggest that females ha ve a higher risk than males because of their arterial overcrossing ratio and BRVO prefer arterial overcrossing. However the insignificant difference between the female and male patients leads us to assume that the effect of sex on BRVO cannot be explained only by local anatomical factors since their effect is only slight.
Effect of Superior and Temporal Clear Corneal Incisions on Astigmatism After Sutureless Phacoemulsification
(Elsevier Science inc, 1998) Simsek, S; Yasar, T; Demirok, A; Cinal, A; Yilmaz, OF
Purpose: To evaluate the effect of superior and temporal clear corneal incisions on astigmatism after sutureless, small incision phacoemulsification. Setting: World Eye Hospital, Istanbul, Turkey. Methods: This prospective study evaluated 40 eyes of 20 patients with cataract having bilateral, sutureless, small incision phacoemulsification by the same surgeon. A superior clear corneal incision was used in all right eyes and a temporal clear corneal incision in ail left eyes. Mean preoperative astigmatism was 0.63 diopter(D) +/- 0.21 (SD) and 0.65 +/- 0.20 D, respectively. Mean patient age was 66.45 years. Patients were examined preoperatively and 1 day, 1 week and 1 and 3 months postoperatively. Results: Three months postoperatively, mean astigmatism was 1.60 +/- 0.37 D in the superior incision group and 0.83 +/- 0.19 D in the temporal incision group. Induced astigmatism calculated by vector analysis was 1.44 +/- 0.31 D and 0.62 +/- 0.28 D, respectively. The temporal incision group had significantly lower astigmatism at all follow-ups (P = .000). Conclusion: Upper lid pressure on the superior corneal incisions led to fluctuating, against-the-rule astigmatism that was significantly higher than that induced by temporal incisions.
Effects of 0.5% and 0.25% Apraclonidine on Postoperative Intraocular Hypertension After Cataract Extraction
(Wichtig Editore, 1998) Simsek, S; Demirok, A; Yasar, T; Çinal, A; Bayram, A; Yilmaz, ÖF
Purpose. We conducted a double-masked, prospective study to evaluate the effect of 0.5% and 0.25% apraclonidine on postoperative intraocular pressure (IOP) in patients undergoing extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation. Methods. Fifty-four patients scheduled for ECCE were randomly divided into three groups of 18. The first group received one drop of 0.50% apraclonidine topically one hour before surgery and immediately after the end of the procedure. The second group received the same regimen but with 0.25% apraclonidine. The third group received artificial fears as the control group. IOP was measured 12 h preoperatively and 6 and 24 h postoperatively. All the measurements were made using the same Goldmann applanation tonometer by the same surgeon who did not know to which group the patient belonged. Results. Preoperative mean IOP was 13.66 +/- 2.76 mmHg in the first group, 14.27 +/- 2.24 mmHg in the second and 14.5 +/- 1.34 mmHg in the control group. The differences were not significant (p = 0.398). Mean IOP at the early postoperative visit (6 h) was significantly lower in the first group (17.44 +/- 4.95 mmHg) than the second (21.78 +/- 7.19 mmHg) and the control group (24.55 +/- 5.65 mmHg) (p < 0.001). Mean postoperative IOP at 24 h was again significantly lower in the first group (14.33 +/- 3.75 mmHg) than the second (17.11 +/- 14.16 mmHg) and the control group (19.61 +/- 3.20 mmHg) (p < 0.001). Conclusions. Our findings indicate that topical 0.5% apraclonidine controlled early postoperative intraocular hypertension after cataract extraction without any side effects, while the 0.25% drops were not effective.
Effects of Fibrovascular Traction and Pooling of Tears on Corneal Topographic Changes Induced by Pterygium
(Nature Publishing Group, 2003) Yasar, T; Ozdemir, M; Cinal, A; Demirok, A; Ilhan, B; Durmus, AC
Aim To investigate the effects of fibrovascular traction and the pooling of tears at the pterygium apex on the corneal topographic changes induced by pterygium. Methods A total of 16 eyes of 14 cases with primary pterygium were included in the study. A computerized corneal topography system was used for corneal topography examinations. Baseline keratographs were taken two times at straight gaze. A repeat corneoscope photograph was immediately obtained in temporal gaze. Then the tears at the pterygium apex were dried with a cellulose sponge, and a new corneoscope photograph was immediately obtained without allowing one to blink. Corneal topographic maps ( numeric maps) were divided into 301 fields in 24 meridians. One colour was allocated to each field, representing its mean refractive power for all groups. In all eyes, keratometric astigmatism at the 3 mm central cornea and total mean corneal refractive power were found. Data were compared using paired-samples two-tailed t-tests. Results Keratometric astigmatism at the 3 mm central cornea was significantly reduced at the temporal gaze (3.10 +/- 2.34 D, t = 3.40, P = 0.027) and dried eyes (2.12 +/- 1.01 D, t = 4.74, P = 0.001) according to the first baseline measurement (4.31 +/- 1.91 D) of the total mean corneal refractive power was found to be 43.45 +/- 1.28 D (39.29-45.87) at the first baseline measurement. There was no change at the temporal gaze (43.54 +/- 1.06 D, P>0.05). However, the total corneal refractive power was significantly higher in dried eyes (44.26 +/- 0.93 D, t = 34.92, P<0.001). The steepest region of corneal topography was a superior quadrant, and the flattest area was a nasal quadrant at the baseline. At the temporal gaze, the cornea was significantly flatter in the superior and inferior sides of the pterygium meridian. After dried pooling of tears, topographic abnormalities returned, and the cornea became more uniform and symmetric. Conclusion We conclude that the pooling of tears at the pterygium apex plays an important role, but fibrovascular traction has no effect on the corneal topographical changes induced by pterygium.
Intraoperative Application of Mitomycin C in the Surgical Treatment of Pterygium
(Wichtig Editore, 1998) Demirok, A; Simsek, S; Çinal, A; Yasar, T
Purpose. To investigate the effectiveness of intraoperative mitomycin C in pterygium surgery. Methods. The effectiveness of intraoperatively administered mitomycin C and the occurrence of postoperative complications were evaluated in 17 patients with two recurrences of pterygium. The authors employed the "bare-sclera technique" and placed a sterile sponge soaked in a 0.02% mitomycin C solution intraoperatively in the episcleral space for 3 minutes. The control group (15 patients) underwent only surgical excision. Patients were followed for 21 to 30 months. Results. The pterygium recurred in one (5.9%) of the 17 patients in group 1 and in six (40%) of the 15 controls. Statistical analysis using Fisher's exact test showed a significant (p=0.027) reduction of recurrences of pterygium in the group treated intraoperatively with mitomycin C. No serious complications or side effects arose during the follow-up period. Conclusions. Mitomycin C administered intraoperatively can be considered an effective treatment to improve the success rate after surgical excision.
Peribulbar Anesthesia: One Versus Two Injections
(Slack inc, 1997) Demirok, A; Simsek, S; Cinal, A; Yasar, T
BACKGROUND AND OBJECTIVE: The authors describe their prospective, randomized study of a single peribulbar injection into the junction of the lateral third and medial two thirds of the lower lid compared with the standard two-injection peribulbar technique. PATIENTS AND METHODS: One hundred twenty patients undergoing elective intraocular surgery were randomly allocated to receive either one or two injections of a mixture of balanced salt solution, 2% lidocaine, 0.5% bupivacaine, and hyaluronidase. Preoperative akinesia was assessed following the injections. At the end of surgery, the patients were asked if they had experienced any pain or discomfort during surgery. RESULTS: There was no significant difference in pain or globe akinesia between the two groups. CONCLUSION: The single peribulbar injection was found to be as effective as the standard two-injection peribulbar technique.
Right Thalamic Hemorrhage Resulting From High-Voltage Electrical Injury
(Elsevier Science Bv, 2004) Çaksen, H; Yuca, SA; Demirtas, I; Odabas, D; Cesur, Y; Demirok, A
A 12-year-old boy was admitted with electrical burn and loss of consciousness. On physical examination his general condition was poor. Extensive burn areas, second and third degree, were present on his face, scalp, bilateral auricles, right cervical region, shoulders, right axilla, upper region of the thorax, and proximal region of the upper extremities. The total burned surface area was about 25%. Pupils were isocoric, but response to light was bilateral poor. He was stuporous and responsive only to pain. Deep tendon reflexes were exaggerated and plantar responses were bilateral extensor. Bilateral decorticate rigidity was noted. Computerized tomography of brain revealed brain edema and right thalamic hemorrhage. Magnetic resonance imaging of brain, examined 25 days after admission, revealed fight thalamic hemorrhage and mild right subdural effusion. He was discharged form hospital 40 days after admission. However, spastic quadriplegia and severe mental retardation remained as sequela. On the 4th month of follow-up, no improvement was noted in his neurological examination. On the 9th month of follow-up, his clinical condition was better, but bilateral electric cataract was diagnosed. Both eyes were operated on and intraocular lenses were implanted with good results. Now he is 16th month of follow-up: neurological examination revealed only mild hemiparesis on the left side and mild articulation disorder. His school performance was moderate and intelligence quotient was 71. Magnetic resonance imaging of brain showed markedly improvement of the hemorrhage. To our best knowledge thalamic hemorrhage resulting from high-voltage electrical injury has not previously been reported in the literature. (C) 2003 Elsevier B.V. All rights reserved.
A Turkish Case of Subcortical/Subependymal Heterotopia Associated With Corpus Callosum Dysigenesis, Craniofacial Dysmorphism, Severe Eye Abnormalities, and Growth-Mental Retardation
(Medecine Et Hygiene, 2003) Çaksen, H; Tuncer, O; Atas, B; Demirok, A; Ünal, Ö; Ikbal, M; Odabas, D
The patient is a 12-year,old boy with a history of learning disability, growth retardation, and strabismus. Weight, height and head circumference were below the 3rd percentile. A cafe-au-lait spot, 1x1 cm a diameter, on the back region and pectus excavatum deformity were diagnosed. He had facial asymmetry a broad nose, sparse eyebrows and eyelashes, a rudimentary frontal sinus, deviation of the nasal septum, and bilateral small maxillary bones. The left orbital fossa was also mildly rudimentary. On eye examination the movements of the left globe to the upward and lateral side were limited and internal strabismus was noted at this side. Visual acuity was 1/10, bilaterally. Bilateral choroid coloboma, glaucoma, vertical and horizontal nystagmus were diagnosed. Fundoscopic examination revealed bilateral optic atrophy and macular and paramacular granulation tissues on the left side. Intelligence quotient was 46. Electroencephalography revealed bilateral frontal slow-wave activity. Visual evoked potential revealed prolonged p100 wave latencies bilaterally. Magnetic resonance imaging of the brain,demonstrated corpus callosum dysgenesis, bilateral subcortical heterotopia in the frontal lobes and subependymal heterotopia in the posterior horn of the left ventricle. Chromosomal analysis revealed a normal male karyotype, 46, XY. Although several cases of heterotopia in association with mental retardation, craniofacial dysmorphism, cerebral, and eye abnormalities have been described the combination of abnormalities diagnosed in our case has not previously been reported. We hypothesize that the combination of subcortical/subependymal heterotopia, corpus callosum dysgenesis, craniofacial dysmorphism, severe eye abnormalities, and growth-mental retardation may be a new syndrome.