Esin F. Erkin

Lens superoxide dismutase and catalase activities in diabetic cataract.

OBJECTIVE Biochemical evidence suggests that the oxidative damage of the lens proteins is involved in the genesis of senile cataract and the development of diabetes-related pathologic changes such as the formation of cataracts. In particular, lens proteins are subject to extensive oxidative modification. Oxidative damage either decreases the antioxidant capacity or decreased antioxidant capacity results in oxidative damage. The purpose of this study was to analyze the activities of the antioxidant enzymes such as Cu,Zn Superoxide Dismutase (Cu,Zn-SOD) and catalase in the cataractous lenses of the type 2 diabetic group and cataractous lenses of the senile group. METHOD Eighteen diabetic cataractous lenses and twenty six senile cataractous lenses were studied. Cu,Zn-SOD activity was measured in lenses by enzymatic method and catalase activity was measured by colorimetric method. RESULTS Cu,Zn-SOD levels were significantly lower in the diabetic cataractous lenses than senile cataractous lenses (respectively 8.052 +/- 0.818, 18.216 +/- 4.217 microg/g prot. p < 0.05). Similarly, catalase levels were significantly lower in the diabetic cataractous lenses than senile cataractous lenses (respectively 0.326 +/- 0.134, 0.665 +/- 0.322 kU/g prot. p < 0.001). CONCLUSION The results of the present study indicate that the antioxidant capacity in the diabetic cataractous lenses were decreased and this result suggests a role of antioxidant enzymes in the genesis of diabetic cataracts.

Effects of betaxolol and latanoprost on ocular blood flow and visual fields in patients with primary open-angle glaucoma.

Purpose To evaluate the effects of betaxolol and latanoprost on ocular blood flow and visual fields in patients with primary open-angle glaucoma (POAG) by means of an obseiver-masked, prospective clinical study. METHODS Thirty-two patients with newly diagnosed POAG were included in the study. The patients were randomized into two groups. The first group was treated with betaxolol 0.50% twice daily and the second group with latanoprost 0.005% once daily. Baseline and post-treatment examinations on the first and third months of treatment included intraocular pressure (IOP) measurement, automated visual field testing, and ocular blood flow assessment. For evaluation of visual fields, mean defect and pattern standard deviation indices were used. Ocular blood flow was assessed by means of color Doppler imaging of the central retinal artery (CRA) and the temporal short posterior ciliary artery (PCA). For each vessel, peak systolic (PSV) and end-diastolic (EDV) blood flow velocities were measured and resistivity index (RI) calculated. Results After exclusion of one noncompliant patient, the study was completed with 31 eyes of 31 patients. Both drugs significantly reduced IOP (p<0.05). The mean IOP lowering effect of latanoprost was significantly higher than that of betaxolol (p=0.03). Visual field indices exhibited no significant changes in either group (p>0.05). There were no significant changes in PSV or EDV measurements of CRA or PCA in either group (p>0.05). RI decreased in both CRA and PCA with both drugs. The mean changes between baseline and 3 month blood flow measurements were not significantly different between betaxolol and latanoprost (p>0.05). CONCLUSIONS Over a treatment period of 3 months, both betaxolol and latanoprost tended to improve ocular blood flow without one of them being superior to the other. The results suggest that the direct (non IOP-dependent) influence on ocular circulation is better for betaxolol than for latanoprost. In addition, neither drug caused significant generalized improvements in visual fields during this period.

THE INFLUENCE OF RELIGIOUS FASTING ON BASAL TEAR SECRETION AND TEAR BREAK-UP TIME

Muslims abstain from food and drink from dawn to sunset during the holy month of Ramadan. An extended strict fasting may influence tear secretion and quality. We investigated changes in basal tear secretion (BTS) and tear break-up time (BUT) at the beginning and at the end of fasting on 32 healthy male patients with a mean age of 22.3 ± 2.9 years. Body weight and urine specific gravity were also determined to assess the extent of dehydration due to fasting. Each case lost 0.1–1.25 kg of body weight while urine specific gravity changes were statistically insignificant. Mean BTS amount was 19.9 ± 10.9 mm at the initial examination and 19.7 ± 11.5 mm at the end of fasting (p=0.9). BUT values were 20.1 ± 9.3 sec at the beginning of fasting and 23.5 ± 14.9 sec at the end of fasting (p=0.19). We found that religious fasting in the winter season does not seem to affect BTS and BUT values in healthy individuals.

Effects of oestrogen replacement therapy on pattern reversal visual evoked potentials.

As a result of a regression in the ovarian functions, oestrogen level in circulation during the menopause drops to 1/50 of its value in the normal reproductive cycle. Excitatory oestrogen increases the sensitivity of the central nervous system to catecholamines by changing the opening frequency of voltage‐related L‐type calcium channels and augmenting the effect of glutamate; in addition it inhibits the formation of gamma‐amino butyric acid (GABA) by the inhibition of glutamate decarboxylase enzyme. It is argued that oestrogen increases transmission in the optic pathways and that oestrogen is responsible for the shorter latency values and higher amplitudes of visual evoked potentials in women. We recorded the monocular pattern reversal visual evoked potentials (PRVEP) of both eyes of 54 post‐menopausal women before treatment and of 30 of them after replacement therapy with Tibolon, and of 24 women receiving placebo treatment. The explicit values of P100 latency of right and left eyes before treatment were 98.8 ± 3.5 and 99.0 ± 3.3 ms, respectively. The explicit values of P100 latency of right and left eyes after placebo treatment were 98.6 ± 3.7 and 98.8 ± 4.0, respectively. The explicit values of P100 latency of right and left eyes after replacement treatment were 94.6 ± 3.7 and 94.8 ± 4.0, respectively. We found a statistically significant decrease in the mean PRVEP latencies and a statistically significant increase in mean amplitudes after replacement treatment (P < 0.001) compared with those before treatment and those after placebo treatment. We attributed the changes in PRVEP values after replacement treatment to the action of Tibolon, which acted as a natural sex steroid and speeded the visual transmission time via the widespread receptors in the central nervous system. It is concluded that PRVEP is an objective electrophysiological assessment method in evaluating the efficiency of hormone replacement therapy in post‐menopausal women.

Effects of Latanoprost and Betaxolol on Cardiovascular and Respiratory Status of Newly Diagnosed Glaucoma Patients

Aims: To investigate the cardiovascular and respiratory effects of topical latanoprost 0.005% and topical betaxolol 0.25% monotherapy in newly diagnosed glaucoma patients. Methods: Fortynewly diagnosed glaucoma patients were enrolled in this prospective, observer-masked, randomized, parallel study. Patients received either latanoprost 0.005% or betaxolol 0.25% for a duration of 3 months. Baseline evaluation included intraocular pressure (IOP) measurement and cardiorespiratory examinations including pulse rate, systolic and diastolic blood pressure measurements and spirometry. These measurements were repeated after 3 months. Results: Both latanoprost and betaxolol reduced IOP significantly (p = 0.001). After 3 months of therapy, the mean pulse rate, systolic and diastolic blood pressure values of the betaxolol group were reduced (p = 0.027, p = 0.07 and p = 0.016, respectively). No significant changes occurred in the cardiovascular measurements of the latanoprost group (p > 0.05). There were no significant changes in any of the spirometric measurements tested for both groups (p > 0.05). Conclusion: Both latanoprost and betaxolol are safe concerning respiratory functions. Betaxolol may cause small changes in the cardiovascular system, suggesting that blood pressure and pulse rates should be checked before and in regular intervals after prescribing it for the elderly. Latanoprost seems to be a safe medication in view of absence of systemic cardiovascular and respiratory side effects.

Penetration of amikacin into aqueous humor of rabbits.

Amikacin is an aminoglycoside antibiotic that has poor corneal penetration due to its hydrophilic properties. The purpose of this study was to compare and evaluate the penetration of amikacin sulfate into aqueous humor of the rabbit eye when applied by different routes and concentrations, namely 100 or 250 mg/ml topical fortified amikacin eye drops, 100 or 250 mg/ml amikacin-embedded soft contact lenses and 25 mg subconjunctival amikacin injection. One hour after application, amikacin was not detectable in any of the 100 mg/ml concentration groups. High levels of amikacin above the minimum inhibitory concentration for susceptible bacteria were detected when applied subconjunctivally and by 250 mg/ml topical fortified routes. Topical fortified amikacin 250 mg/ml reached the highest value in the aqueous (p < 0.05). Our results point out the poor corneal penetration of amikacin in standard concentrations from the intact rabbit cornea and that subconjunctival injections might provide satisfactory penetration.

Axial length measurement and asteroid hyalosis.

PURPOSE To evaluate the effect of asteroid hyalosis on automated and manual A-scan axial length measurements. SETTING Celal Bayar University School of Medicine, Manisa, Turkey. METHODS A case-control study comprised 15 patients with unilateral asteroid hyalosis. The uninvolved eyes were used as controls. Axial length measurements by manual and automated A-scan biometry were performed in both eyes. The main outcome measures were comparisons between manual and automated measurements in asteroid hyalosis eyes with those in control eyes and the assessment of density of asteroid bodies on B-scan photographs. RESULTS Statistical analysis revealed no significant difference between axial lengths of asteroid hyalosis eyes and those in control eyes with automated (P = .524) or manual (P = .163) methods. Using automated biometry, 1 patient (7%) had a false (6.23 mm) short axial length measurement in the eye with asteroid hyalosis. There were no significant correlations between manual versus automated measurement differences and the density of the asteroid bodies. CONCLUSIONS The axial length of the eye without asteroid hyalosis can be used to calculate intraocular lens power if the patient has no history of clinical anisometropia.

Unilateral Refractive Keratotomy for Anisometropia

BACKGROUND In anisometropia, the asymmetry of refractive error produces disparity of image magnification (aniseikonia) that can create visual discomfort, especially when asymmetry is 3.00 diopters or more. METHODS A prospective study of 20 eyes of 20 patients between 18 and 61 years of age who underwent unilateral radial and/or transverse keratotomy was conducted; results of at least 12 months follow-up are presented. The efficacy of keratotomy was evaluated by the following criteria: 1) change in spherical and cylindrical refraction, 2) decrease in refraction difference between two eyes of each patient, 3) change in spectacle-corrected visual acuity, and 4) change in binocular vision functions and asthenopic complaints. RESULTS Mean decrease in spherical refractive error was 3.66 +/- 1.58 D (range, 1.25 to 7.50 D) and 2.08 +/- 0.81 D (range, 1.00 to 3.50 D) in astigmatic refraction. The mean refraction difference between two eyes was 4.90 +/- 2.20 D preoperatively, and this difference regressed to 1.79 +/- 1.42 D postoperatively. Spectacle-corrected visual acuity increased in seven eyes (35%), remained the same in 12 eyes (60%) and decreased in one eye (5%). All patients reported relief of asthenopic complaints. Fusion amplitudes increased in 12 (60%) patients. Stereoscopic vision improved in five (25%) patients. CONCLUSION Monocular refractive keratotomy can significantly decrease anisometropia.