Intravitreal bevacizumab treatment of retinal telangiectasis complicated by subretinal neovascularization

BACKGROUND

Idiopathic perifoveal telangiectasia (IPT) is a disorder characterized by focal parafoveal capillary dilatation of unknown cause. Photodynamic therapy (PDT) was reported to be efficacious in the treatment of subretinal neovascularization (SRN) associated with idiopathic juxtafoveal retinal telangiectasis. However, visual improvement is limited.

METHODS

We describe the clinical, angiographic, and optical coherence tomography findings for a patient with IPT complicated with SRN and treated with PDT and bevacizumab.

RESULTS

The patient underwent 2 sessions of PDT; however, metamorphopsia persisted, and visual acuity further decreased to 20/100 after the second PDT. Two injections of intravitreal bevacizumab (1.25 mg) were administered after PDT. Visual acuity increased dramatically from 20/100 to 20/25 after the injections. Four months after the second injection, there was no recurrence, and the patient was asymptomatic.

CONCLUSION

Intravitreal bevacizumab treatment should be considered for patients with SRN associated with perifoveal telangiectasis, especially after insufficient therapeutic response to PDT.

The use of blood culture bottles in endophthalmitis

PURPOSE

To study the use of blood culture bottles for culturing vitreous specimens in acute-onset postoperative infectious endophthalmitis cases.

METHODS

Forty-eight eyes of 48 patients with mean age of 66.4 +/- 14.7 years with postoperative endophthalmitis that occurred within 6 weeks after ocular surgery, presenting from June 2001 to January 2005, were retrospectively studied. Vitreous fluid specimens of these patients were cultured in blood culture bottles. The measured outcome is the yield of positive culture.

RESULTS

Vitreous specimens yielded positive in 34 of 48 (70.8%) eyes with blood culture bottles. The most common organism isolated was Staphylococcus epidermidis in 17.6% (6/34) of cases.

CONCLUSION

The direct inoculation of vitreous specimens into the blood culture bottles is easy to perform, with a high yield positive rate (70.8%). It may be an alternative to conventional culture media for culturing vitreous specimen in infectious endophthalmitis especially in clinics or hospitals that are unable to have adequate microbiology laboratory facilities.

Complicated Flap Creation With Femtosecond Laser After Radial Keratotomy

PURPOSE

To report a case of laser in situ keratomileusis (LASIK) that used the Intralase femtosecond laser 14 years after radial keratotomy (RK) for residual myopic astigmatism.

METHODS

A 39 year-old male patient had undergone a bilateral RK operation for myopic correction. The manifest refraction was -1.25 -3.00 x 175 D, with uncorrected visual acuity (UCVA) of 20/50 and best-corrected visual acuity (BCVA) of 20/20. The central and thinnest pachymetry measurements were 582 and 576 mum, respectively, by Orbscan II.

RESULTS

Intralase was used for LASIK, and initially, a loss of suction was seen during flap formation. The flap could be created again at the same intracorneal plane. During flap lifting, the RK incisions were separated, and one of the RK incisions progressed to the corneal center with the force applied by the blunt spatula. No piece was separated completely from the flap. Excimer laser treatment and flap repositioning could be done without any problems. At the fifth postoperative month, his UCVA was 20/20. All RK incisions seemed well aligned. There was no haze or epithelial ingrowth.

CONCLUSIONS

This case showed that the Intralase femtosecond laser not only has no unique benefit as opposed to the mechanical keratome for post-RK eyes but also can lead to serious complications. We recommend that femtosecond laser flap formation not be used in post-RK eyes.

Evaluation of the Corneal Topographic Characteristics of Keratoconus With Orbscan II in Patients With and Without Atopy

PURPOSE

: To analyze the differences in corneal topography in keratoconus patients with and without atopy.

METHODS

: In the Beyoglu Eye Research and Training Hospital Refractive Surgery Department, corneal examination with the Orbscan II device (Bausch & Lomb) was done to all patients between May and June 2004 who were diagnosed as keratoconus with corneal topography findings and who did not have any surgical procedure. The atopy grading was done according to the criteria of the UK Atopy Study Group (1994). Patients were divided into 2 groups according to the presence of atopy. The Orbscan findings of the 2 groups were compared.

RESULTS

: Among 70 keratoconus patients, 33 patients had partial or full atopy. Sixty-six eyes of the 33 patients were classified as the atopic group, whereas 74 eyes of the remaining 37 patients were classified as the control group. The mean age of the patients was 27.7 +/- 9.5 years in the atopic group and 26.9 +/- 9.5 years in the control group. The central corneal thickness was 428.5 +/- 37.1 mum in the atopic group and 491.8 +/- 56.3 mum in the control group. There was a statistically significant difference between the mean central and thinnest corneal pachymetric readings, the distance of thinnest point to corneal center, anterior and posterior elevation values, distances of the anterior and posterior elevation to the central cornea, and irregularity indexes in the 2 groups (P < 0.05).

CONCLUSIONS

: This study shows that corneal topographic and pachymetric characteristics of keratoconus may be different in atopic eyes from those in nonatopic eyes. Atopic keratoconus patients could possibly be evaluated as a separate entity in keratoconus disease.

Radial keratotomy for the optical rehabilitation of mild to moderate keratoconus: more than 5 years' experience

PURPOSE

To present the authors' long-term experience of radial keratotomy (RK) for the optical rehabilitation of patients with mild to moderate keratoconus--central corneal thickness of greater than 400 microm and without apical scarring.

METHODS

In this observational, noncomparative series of cases, all consecutive patients with mild or moderate keratoconus, treated by RK between 1990 and 2002, with at least 1 year follow-up were included. A total of 170 eyes of 96 patients were investigated. Mean follow-up was 42.08 +/- 28.14 months. Visual acuity, refraction, corneal curvature, central corneal thickness, and complications were evaluated.

RESULTS

In all of the control visits, mean uncorrected and best spectacle corrected visual acuities were better than preoperative values (p<0.0001). Preoperative myopic spherical refraction decreased significantly (p<0.0001), and remained relatively unchanged throughout the follow-up (p=0.43). A small but statistically significant decrease from baseline was ob-served in astigmatism (p=0.038), which almost disappeared 1 year after the surgery (p=0.47). The surgery produced a statistically significant flattening of the corneal curvature (p<0.0001). Central corneal thickness did not change significantly (p>0.05) in either control visit. In 33 eyes (19.4%), re-deepening of the incisions was required. In 3 eyes (1.8%) penetrating keratoplasty was performed, due to disease progression in 2 eyes (1.2%) and acute traumatic hydrops in 1 eye (0.6%). In 4 eyes (2.2%) microperforation, in 2 eyes (1.2%) macroperforation, in 1 eye (0.6%) infectious keratitis, and in 1 eye (0.6%) hyperopic shift occurred.

CONCLUSIONS

RK surgery was found to be a reasonable option for the rehabilitation of a selected group of keratoconus patients in the early or moderate stages.

Intraocular pressure control after clear corneal phacoemulsification in eyes with previous trabeculectomy: a controlled study

PURPOSE

To compare intraocular pressure (IOP) control in eyes with or without clear corneal phacoemulsification following trabeculectomy.

METHODS

The study group included 30 eyes that underwent uneventful clear corneal phacoemulsification and foldable intraocular lens implantation following trabeculectomy without antimetabolites. Thirty eyes that had undergone filtering surgery without cataract extraction were selected as controls. Case and control groups were matched with respect to age, gender, IOP, number of glaucoma medications, glaucoma type (primary open-angle glaucoma/pseudoexfoliative glaucoma), trabeculectomy time and follow-up. Comparisons between the study and control groups (intergroup) and within the same group at different time-points (intragroup) were performed for IOP, glaucoma medications and bleb morphology. Success rates were investigated by Kaplan-Meier survival analysis and the factors influencing final success by logistic regression.

RESULTS

Intraocular pressure (p = 0.04) and glaucoma medications (p = 0.001) increased during an average follow-up of 26.1 +/- 9.9 months in both groups. Intragroup differences became statistically significant after the 6-month visit, but intergroup differences remained insignificant. Bleb height decreased significantly following phacoemulsification in the study group (p = 0.017). Success rates decreased with time in both groups, with no intergroup difference (p = 0.46). The final success rate was negatively correlated with IOP and number of glaucoma medications used at the study entry, while there was a positive correlation between the baseline and final success rates.

CONCLUSION

Trabeculectomy success decreased in a time-dependent manner in eyes with and without subsequent phacoemulsification. Uncomplicated clear corneal phacoemulsification was not found to have any additional unfavorable influence on IOP control in eyes with filtering blebs.

Anterior chamber depth, iridocorneal angle width, and intraocular pressure changes after uneventful phacoemulsification in eyes without glaucoma and with open iridocorneal angles

PURPOSE

To investigate the influence of uneventful phacoemulsification on anterior chamber depth (ACD), iridocorneal angle (ICA) width, and intraocular pressure (IOP) in nonglaucomatous eyes with open ICA preoperatively.

SETTING

Beyoglu Eye Education and Research Hospital, Istanbul, Turkey.

METHODS

Fifty-three eyes of 49 patients were evaluated for 6 months postoperatively. The nonparametric Wilcoxon signed rank test was used to compare preoperative and postoperative IOP, ACD, and ICA width. Univariate and multivariate regression analyses were used to evaluate the relationships between IOP, ACD, and ICA width and between preoperative patient characteristics.

RESULTS

The mean preoperative IOP of 15.1 mm Hg +/- 2.8 (SD) dropped postoperatively to 13.4 +/- 3.4 mm Hg at 1 day, 13.3 +/- 2.6 mm Hg at 1 week, 13.2 +/- 3.1 mm Hg at 1 month, 13.3 +/- 2.7 mm Hg at 3 months, and 14.1 +/- 2.5 mm Hg at 6 months (P<.05). The mean preoperative ICA grade of 2.97 +/- 0.72 increased to 3.55 +/- 0.48 at 1 week and 3.68 +/- 0.45 at 1 month (P<.05). The mean preoperative ACD of 3.06 +/- 0.49 mm increased to 3.57 +/- 0.47 mm at 4 weeks, 3.69 +/- 0.32 mm at 1 month, and 3.70 +/- 0.36 mm at 3 months (P<.05). The IOP decrease was not correlated with the changes in ICA width or ACD. Multiple regression analysis showed preoperative IOP was the single predictor of the postoperative IOP drop (P<.001).

CONCLUSIONS

In nonglaucomatous eyes with an open ICA preoperatively, uneventful phacoemulsification reduced IOP, increased ACD, and widened the ICA. The changes were statistically significant over 6 months.

Prospective, Paired Comparison of Laser in situ Keratomileusis and Laser Epithelial Keratomileusis for Myopia Less Than -6.00 Diopters

PURPOSE

To compare visual and refractive results, contrast sensitivity, and tear stability after laser in situ keratomileusis (LASIK) in one eye and laser epithelial keratomileusis (LASEK) in the fellow eye for low myopia.

METHODS

Patients diagnosed with low myopia, with a maximum difference of 1 D between their two eyes, were randomly assigned to receive LASEK on one eye and LASIK on the other eye. A total of 64 eyes of 32 patients with a mean age of 26.83 +/- 5.33 years were included in the study. Preoperative myopia ranged from -1.00 to -6.00 D. Follow-up was 6 to 12 months. Uncorrected (UCVA) and best spectacle-corrected visual acuity (BSCVA), Schirmer test results, tear break-up time, corneal asphericity, corneal uniformity index, predicted corneal acuity, and contrast sensitivity values were compared with preoperative values. A Wilcoxon test was used for statistical comparisons and a P-value less than .05 was considered significant.

RESULTS

At 6 months after surgery, there was no statistically significant difference in UCVA, BSCVA, spherical and cylindrical refractive error, Schirmer test, or tear break-up time between groups. Contrast sensitivity values in the LASIK eyes were lower in comparison to preoperative values, but there was no change in the LASEK group.

CONCLUSIONS

Based on 6-month results, LASEK for low myopia was safe and effective with predictable results, offered early refractive stability, and may be considered an alternative for LASIK.

Capsular tension ring implantation after capsulorhexis in phacoemulsification of cataracts associated with pseudoexfoliation syndrome. Intraoperative complications and early postoperative findings

PURPOSE

To evaluate the effect of an endocapsular tension ring in preventing zonular complications during phacoemulsification of cataracts associated with pseudoexfoliation syndrome.

SETTING

Eye Clinic of Beyoğlu Education and Research Hospital, Istanbul, Turkey.

METHODS

A prospective randomized study comprised 78 eyes with cataract and pseudoexfoliation syndrome that were randomly divided into 2 groups. The age, sex, cataract density, iridodonesis, axial length, anterior chamber depth, best corrected visual acuity (BCVA), and intraocular pressure (IOP) were matched between groups. In 39 eyes, a capsular tension ring (CTR) was implanted after capsulorhexis and hydrodissection but before nucleus emulsification. Thirty-nine eyes that did not have a CTR implanted served as a control. The main outcome measures were the rates of intraoperative zonular separation and capsular fixation of a foldable intraocular lens (IOL). Posterior capsule rupture without zonular dialysis, vitreous loss, corneal edema, fibrin in the anterior chamber, BCVA, and IOP in the immediate postoperative period were also compared between the 2 groups.

RESULTS

Five eyes (12.8%) in the control group and no eye in the CTR group had intraoperative zonular separation (P =.02). Posterior capsule rupture without zonular separation occurred in 3 eyes (7.7%) in the control group and 2 (5.2%) in the CTR group. Capsular IOL fixation was achieved in 37 eyes (94.9%) in the CTR group and 31 eyes (74.3%) in the control group (P =.012). The difference in BCVA was not statistically significant between the 2 groups (P =.44); however, uncorrected visual acuity (UCVA) was significantly better in the CTR group (P =.026).

CONCLUSION

In cases of cataract associated with pseudoexfoliation syndrome, implanting a CTR before phacoemulsification of the nucleus reduced intraoperative zonular separation, increased the rate of capsular IOL fixation, and improved UCVA.

Influence of scan radius correction for ocular magnification and relationship between scan radius with retinal nerve fiber layer thickness measured by optical coherence tomography

PURPOSE

To investigate how optical coherence tomography (OCT) modifies the preset scan parameters to correct the errors resulting from ocular magnification, the influence of examiner's final correction of those already modified parameters on retinal nerve fiber layer (RNFL) thickness measurements, the induced change on RNFL thickness measurements and RNFL estimated integrals (RNFL(estimated integrals)) by adjusting the actual scan radius during RNFL examinations performed by OCT.

METHODS

Thirty-five healthy patients underwent an RNFL examination by OCT four times using different scan radii. The first scan was performed with the preset circular scan diameter of 3.46 mm; the actual scan diameter was different, however, because it was modified by the OCT instrument. The second, third, and fourth scans were generated after readjusting the already modified scan diameter by the examiner to 3.46, 3.20, and 3.60 mm. The relationship of axial length and refractive error with the actual scan radius (with ocular magnification calculated by OCT), with the influence of the examiner's final correction on RNFL thickness measurements, with the relationship between scan radius with RNFL thickness measurements, and with RNFL(estimated integrals) were investigated.

RESULTS

The actual scan diameter was found to be primarily determined by axial length (R = 0.97, P < 0.0001), but the influence of refractive error was small (R = -0.26, P = 0.067). Final correction of the actual scan radius by the examiner had a significant influence on RNFL thickness measurements (P = 0.025). RNFL thickness measurements obtained without correction of the actual scan radius for magnification were found to be inversely correlated with axial length (R = -0.54, P = 0.001), whereas no similar relationship was found when RNFL thickness measurements were obtained with correction (R = 0.21, P = 0.11). A reciprocal relationship between 1/scan radius with RNFL thickness measurements (they tended to be thinner as scan radii were increased) was found (R = 0.41, P = 0.169), but RNFL(estimated integrals) areas were found to be independent of the scan radius (P = 0.521).

CONCLUSION

To increase the accuracy of RNFL thickness measurements, it will be appropriate for the examiner to manually correct the actual scan parameters to the desired or preset ones after their automatic modification performed by the OCT instrument. Keeping the actual scan radius constant for repeated exams is also recommended because RNFL thickness measurements were found to depend on scan size. Alternatively, RNFL(estimated integrals) could be used because they were found to be independent of the scan size.

The refractive changes and long-term (3 years) results of radial keratotomy performed at high altitude

PURPOSE

To evaluate the development of regression or progression following radial keratotomy (RK) performed at high altitude (1,720 meters) at long-term follow-up (3 years).

METHODS

Thirty-nine eyes of 21 myopia patients (between -3.25 D and -11.00 D) whose ages were 19-32 years were included in the study. The RK procedures were performed in standard Russian style.

RESULTS

The average spherical equivalent cycloplegic refractions were -5.49 D +/- 2.08 (SD) preoperatively, -1.64 +/- 1.59 D in the short-term (3.41 +/- 1.46 months) and -1.40 +/- 1.71 D in the long-term (30.72 +/- 4.36 months) follow-up period. There was no statistically significant difference between these values at the short- and long-term follow-up measurements (t = -1.57, P =.12).

CONCLUSIONS

The refractive changes following RK performed at high altitude occur through a combination of both the direct effect of reduced barometric pressure and the edematous corneal expansion because of hypoxia. An ophthalmologist performing RK surgery at high altitude must consider the long-lasting therapeutic effects of high altitude surgery compared to surgery at sea level.

Posterior capsule opacification 3 years after implantation of an AcrySof and a MemoryLens in fellow eyes

PURPOSE

To compare the rates of lens epithelial cell (LEC) migration and posterior capsule opacification (PCO) 1 and 3 years after sutureless small incision phacoemulsification and in-the-bag implantation of 2 acrylic polymer intraocular lenses (IOLs)-the AcrySof and MemoryLens-in fellow eyes of patients.

SETTING

Eye Clinic, Beyoğlu Education and Research Hospital, Istanbul, Turkey.

METHODS

Fifty patients with no systemic or ocular problems that would interfere with postoperative visual acuity were included in this prospective study. Each patient had in-the-bag implantation of an AcrySof IOL in 1 eye and a MemoryLens in the fellow eye in a randomized fashion after uneventful phacoemulsification through a sutureless clear corneal incision.

RESULTS

At 1 year (n = 32 patients), there was no significant difference between fellow eyes in postoperative best corrected visual acuity (BCVA) and contrast sensitivity. In the MemoryLens group, 10 eyes (31.3%) had PCO and 9 (28.1%), LEC migration. In the AcrySof group, no eye had PCO and 2 eyes (6.3%) had LEC migration (P <.001). At 3 years (n = 21 patients), 1 eye (4.7%) in the AcrySof group had PCO and 3 eyes (14.4%) had LEC migration without PCO. In the MemoryLens group, 1 eye (4.7%) had a clear posterior capsule, 11 eyes (52.4%) had LEC migration, and 9 eyes (42.9%) had PCO (P <.001). A neodymium:YAG capsulotomy was required in 4 eyes (19.0%) in the MemoryLens group but no eye in the AcrySof group. At 3 years, BCVA was lower in the MemoryLens group than in the AcrySof group (P <.05).

CONCLUSION

The 3 year clinical data of fellow eyes indicate that the AcrySof IOL causes less PCO than the MemoryLens.

Relation of optic disc topography and age to thickness of retinal nerve fibre layer as measured using scanning laser polarimetry, in normal subjects

AIMS

To evaluate the relation of the optic nerve head topographic measurements and age with the thickness of the retinal nerve fibre layer (RNFL) in normal Caucasoid subjects by means of scanning laser polarimetry and tomography.

METHODS

Topographic optic disc measurements and RNFL thickness values of 38 normal Caucasoid subjects of both sexes aged 20 to 78 were measured using a confocal scanning laser ophthalmoscope and a confocal scanning laser polarimeter. One eye was randomly selected for statistical analysis. The effects of optic disc size, age, and optic disc head topographic measurements of total and regional RNFL thickness were evaluated.

RESULTS

Age showed a significant correlation with the integral of the total RNFL thickness (R=-0.341, p<0.05). The optic disc size showed a significant correlation with the integral of the total, superior, and inferior quadrant RNFL thickness (R=0.425, p<0.01), (R=0.361, p<0.05), (R=0.468, p<0.05). Neuroretinal rim area (NRA) had a correlation with the superior and inferior quadrant RNFL thickness values (R=0.339, p<0.05) (R=0.393, p<0.05). There was no significant correlation between the other optic disc topographic measurements and RNFL thickness values (p>0.05).

CONCLUSION

The thickness of total as well as superior and inferior quadrant peripapillary RNFL as measured by scanning laser polarimetry increased significantly with an increase in optic disc size. The cross sectional area occupied by superior and inferior polar RNFL increased significantly with an increase in NRA. The total cross sectional area occupied by RNFL decreased significantly with an increase in age. The effects of optic disc size, age, and NRA should be considered when the peripapillary RNFL thickness is evaluated.

Phakic posterior chamber plate intraocular lenses for high myopia

PURPOSE

Refractive correction of high myopia with phakic minus power intraocular lenses (IOLs) may give dramatic visual results. Various types of lenses developed for this purpose have not gained widespread use due to complications. Long-term results and complications of phakic posterior chamber lenses are yet unknown. The purpose of this study was to evaluate long-term refractive results and complications of early design phakic posterior chamber lenses.

METHODS

Thirty-four high myopic eyes implanted with phakic posterior chamber IOLs designed by Fyodorov were evaluated retrospectively. Follow-up time ranged from 36 to 62 months. Corneal endothelial cell counts were made at the central cornea preoperatively and in the sixth month in 18 eyes and in the twelfth month in 14 eyes.

RESULTS

Preoperative refractions were between -7.75 and -21.00 D; refractions at the end of the follow-up period were between -5.75 and +3.00 D. Sixty-three percent of eyes were in the +/-2.00-D range. Endothelial cell loss was 9% at 6 months and 10.22% at 12 month. The difference in endothelial cell counts at 6 and 12 months was not statistically significant.

CONCLUSIONS

Early design phakic posterior chamber IOLs implanted in this study were developed by Fyodorov and are not used currently. These IOLs provided a stable and reversible refractive correction without leading to cataract formation. Endothelial loss was limited to surgical trauma. Moderate predictability of refractive correction and frequent decentrations with these lenses were linked to the early design of these IOLs.

Changes in anterior chamber depth and axial length measurements after radial keratotomy

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

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.

Effect of superior and temporal clear corneal incisions on astigmatism after sutureless phacoemulsification

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 all 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.

The effect of altitude on radial keratotomy

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 hypotheses 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.