Hikmet Basmak

Reproducibility and tolerability of the ICare rebound tonometer in school children.

PurposeTo establish the intraobserver and interobserver reliability of the rebound tonometer (RBT) in healthy schoolchildren and to test patient tolerance in an unanesthetized eye. Subjects and MethodsTo examine the reproducibility of the RBT, 2 experienced ophthalmologists undertook 3 consecutive intraocular pressure (IOP) measurements with the RBT without an anesthetic in 304 eyes of 152 healthy schoolchildren. Any pain or discomfort experienced by the children was recorded. Intraobserver and interobserver reliabilities were established by calculating correlation coefficients (r). ResultsOf the 152 patients, 78 (51.3%) were males and 74 (48.7%) were females. The mean patient age was 11.2±2.6 years (range: 7 to 15 y). Mean IOP values obtained by examiners 1 and 2 were 16.48±2.82 mm Hg and 17.27±3.27 mm Hg for the right eyes and 17.15±3.36 mm Hg and 17.06±3.21 mm Hg for the left eyes. Intraobserver correlation coefficients for examiner 1 were 0.970 for the right eyes and 0.974 for the left eyes. For examiner 2, intraobserver correlation coefficients were 0.963 for the right eyes and 0.970 for the left eyes. The interobserver correlation coefficients were 0.798 for the right eyes and 0.858 for the left eyes (all P<0.0001). With the RBT, 98.6% of the subjects felt no pain and/or discomfort. ConclusionsMeasurement of IOP with the RBT is a highly reproducible method in schoolchildren showing high intraobserver and interobserver correlation and it seems to be very comfortable when performing IOP measurements in schoolchildren without an anesthetic.

Measurement of angle kappa with synoptophore and Orbscan II in a normal population.

PURPOSE To obtain normative values of angle kappa in a normal population by synoptophore and Orbscan II and to compare the reliability of these devices. METHODS Three hundred consecutive healthy individuals were enrolled in the study. A complete orthoptic and ophthalmologic examination was performed. Synoptophore and Orbscan II corneal topography were used to measure angle kappa. To evaluate the association of the angle kappa and refraction measures, individuals were further classified according to the degree of myopia and hyperopia. The spherical equivalent error measures were grouped into six categories: > or = -3.00 diopters (D); -2.75 to -1.50 D; -1.25 to -0.50 D; +0.50 to +1.25 D; +1.50 to +2.75 D; and > or = +3.00 D. Paired t test and Pearsons correlation test were used for statistical analysis. RESULTS The mean age of the individuals was 28.74 +/- 1.63 years (range: 20 to 40 years). The angle kappa values obtained by synoptophore and Orbscan II were normally distributed. In the myopic group, angle kappa values decreased significantly towards negative refractive errors. In contrast, a correlation existed between large positive angles and positive refractive errors in the hyperopic group. Angle kappa values obtained by Orbscan II were significantly higher in all groups when compared to synoptophore (P < .0001). A significant correlation was noted between synoptophore and Orbscan II measurements (r = 0.932, P < .0001). CONCLUSIONS A significant correlation exists between positive refractive errors and large positive angle kappa values. Refractive surgeons must take into account angle kappa, especially in hyperopic patients, to avoid complications related to decentration of the ablation zone.

The influence of central corneal thickness and corneal curvature on intraocular pressure measured by tono-pen and rebound tonometer in children.

PurposeTo find out the effect of central corneal thickness (CCT) and radius of the corneal curvature on intraocular pressure (IOP) measurements using rebound tonometer (RBT) and Tono-Pen in healthy schoolchildren. MethodsIOP was measured with Tono-Pen and RBT, respectively, in 165 healthy schoolchildren with a mean age 9.8±3.1 (range: 7 to 12 y) years. Corneal radius of curvature (in mm) was determined using a keratometer before CCT and IOP measurements. CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made. The effect of CCT, radius of the corneal curvature, and sex on measured IOP was evaluated by linear regression analysis. ResultsThe mean IOP readings were 17.47±2.7 mm Hg using Tono-Pen, and 16.81±3.1 mm Hg using RBT. Tono-Pen measured IOP values slightly greater than that of RBT (P=0.006). Mean CCT was found to be 561.37±33 μm. A significant association between measured IOP and CCT was found with each device (r=0.220 for the Tono-Pen, r=0.373 for the RBT; P=0.006 for the Tono-Pen and P<0.0001 for the RBT). The IOP increased 2.2 and 3.7 mm Hg for every 100-μm increase in CCT for the Tono-Pen and the RBT, respectively. The relation between IOP and CCT was not different for boys and girls. Mean radius of the corneal curvature readings was 7.68±0.41 mm (42.75±1.37 D) for both sexes. There was no significant relationship between either the mean corneal curvature readings, or CCT and IOP (r=0.02; P=0.4 for CCT and r=0.01; P=0.5 for IOP). ConclusionsBoth the Tono-Pen and RBT have a systematic error in IOP readings caused by its dependence on CCT. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in children, like in adults. The corneal radius of curvature had no significant effect on measured IOP with each device.

Retinopathy of prematurity: screening guidelines need to be reevaluated for developing countries.

Purpose. Timely screening of premature babies is an important initial step in the management of retinopathy of prematurity (ROP) as earlier treatment results in improved visual prognosis. Screening criteria for ROP currently recommended by the American Academy of Pediatrics may not be applicable in developing countries. The aim of the present study is to find out the incidence of ROP in infants with a gestational age (GA) of ≥32 weeks in Eskisehir, Turkey, to provide information to assist in determining screening criteria. Methods. A total of 96 infants with a GA of 32–35 weeks who were referred for ROP between January 1, 2004, and December 31, 2008, were studied. ROP screening, follow-up, and appropriate therapies were applied. Results. During ROP screening, there were 42 of 96 (43.8%) infants with no ROP. A total of 54/96 (56.2%) infants were noted to have ROP. Among all infants, 7 (7.3%) had threshold ROP. Two infants with threshold disease were born at the 32nd, 2 at the 33rd, and 3 at the 34th week of gestation. The mean birthweight was 1857.9 (range 1060–3200) grams. Conclusions. In our study, it was found that more mature infants may also develop threshold ROP and require early treatment. After more information is gained and widespread screening, screening protocols covering more mature infants can be designed especially for developing countries.

Der Effekt der Levodopatherapie auf das visuell evozierte Potential und die Sehschärfe in der Amblyopie

Amblyopia represents the most common form of visual impairment in children, affecting approximately 2% of the population. To determine the efficacy of the dopamine agonist levodopa for childhood amblyopia, a double-masked, placebo-controlled randomised study was performed on 32 amblyopic children with central fixation between 4 and 17 years. Subjects received 2 mg/kg levodopa benzeraside or placebo 3 times per day over a 1 week period. Estimates of visual acuity for each eye (Snellen visual acuity) were obtained, and pattern-shift visually evoked potentials (VEP) were examined by an opthalmologist and a neurologist. At the end of the dosing regimens, the levodopa group was significantly improved in visual acuity by 1.4 lines and pattern VEP amplitudes. No changes could be detected after placebo administration. One week after the termination of the treatment, Snellen line acuity and pattern VEP amplitude were decreased to pretreatment levels. The transient effect of levodopa points to a long-term treatment with the substance. Our results should therefore encourage further long-term clinical trials investigating the therapeutic potential of levodopa in amblyopia.

The reliability of central corneal thickness measurements by ultrasound and by Orbscan system in schoolchildren.

Purpose: To compare the central corneal thickness measurements obtained by ultrasound (US) pachymetry and the Orbscan II system in healthy schoolchildren. Methods: A total of 356 schoolchildren aged 7 to 12 years underwent central cornal thickness (CCT) measurement with Orbscan II and ultrasonic pachymetry. All eyes were examined first with the Orbscan II and then by US pachymetry. The mean of the difference, standard deviation (SD), and 95% limits of agreement, with and without applying the acoustic correction factor, were determined. The differences between the devices in measuring mean CCT were calculated with paired-sample t test. Pearson correlation test was used to determine the correlation between variables. p < 0.05 was considered to be statistically significant. Linear regression analysis was used to quantify the correlation between the two methods. Results: Orbscan II measurements were significantly higher than US pachymetry measurements without applying the manufacturer-recommended acoustic correction factor (0.92) correction (580.39 ± 37 μm and 562.95 ± 32 μm, respectively) (p < 0.0001). When this acoustic correction factor was applied, the Orbscan II measurements demonstrated significantly lower results when compared with those of US pachymetry (533.96 ± 34 μm and 562.95 ± 32 μm, respectively) (p < 0.0001). The linear regression analysis lines showed approximately 45-degree slope indicating a strong correlation between these methods (US pachymetry = 145.71 + 0.72 × Orbscan II value without acoustic correction factor (μm), r = 0.89, p < 0.0001). There was a high degree of variability in differences between the 2 devices in individual subjects. The range was between 25 to −55 μm without the acoustic correction factor and 67 to −5 μm with the acoustic correction factor. Conclusions: Although US pachymetry and Orbscan II demonstrated a strong linear correlation, there was a high degree of variability in differences between the two devices in individual subjects who participated.

Two-year interval changes in Orbscan II topography in eyes with keratoconus

PURPOSE: To define topographic characteristics and quantitatively document changes in corneal topography parameters in relation to the progression of keratoconus over time using the Orbscan II topography system (Bausch & Lomb). SETTING: Eskisehir Osmangazi University Medical School, Department of Ophthalmology, Meselik, Eskisehir, Turkey. METHODS: This study comprised 79 eyes (79 patients) with keratoconus who had Orbscan II topography examinations at least twice with a mean interval of 24 months ± 3.2 (SD). Topographic parameters including location radius, elevation compared to a best‐fit sphere, pachymetry, mean tangential curvature, and mean spheric curvature were evaluated with special reference to the central point of the cornea, the apex, and the thinnest point. The change in each parameter was calculated using the paired t test. RESULTS: The mean patient age was 32.4 ± 15.2 years. The increase in apex elevation (mean: 0.056 ± 0.033 mm baseline versus 0.069 ± 0.037 follow‐up) (P<.02) and displacement of the location of the apex were statistically significant. The mean thinnest‐point pachymetry decreased from 369 ± 53 μm at baseline to 343 ± 61 μm at follow‐up (P = .03). The mean simulated keratometry minimum value was 48.21 ± 5.5 diopters (D) and 54.09 ± 6.2 D, respectively, a statistically significant increase (P = .02). The mean radius, mean elevation, mean tangential, and mean spheric curvatures of the apex did not change significantly. CONCLUSION: The Orbscan II topography system provided useful and detailed numerical information on keratoconic corneas and documented their progression quantitatively by serial topographic analysis.

Lenstar versus ultrasound for ocular biometry in a pediatric population.

Purpose. To compare the central corneal thickness (CCT), axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) measured with Lenstar with those obtained with ultrasound pachymetry and A-scan contact ultrasound (ASU) in children. Methods. ODs of 565 school children were included. All measurements were obtained 30 min after instilling 1% tropicamide. For each instrument, three consecutive measurements per each child were performed. Initially, examiner 1 performed measurements with Lenstar to obtain CCT, AL, ACD, and LT. Later, examiner 2 performed measurements with corneal pachymetry to obtain CCT. Finally, ASU was used by examiner 2 to obtain AL, ACD, and LT. Four parameters obtained with Lenstar were compared with those obtained with pachymetry and ASU using Pearson correlation coefficients (r) and Bland-Altman analyses. Result. Lenstar measurements were obtained in 557 of 565 subjects(mean age; 10.48 ± 2.11 years, mean spherical equivalent of the ODs; +0.47 ± 1.18 diopters) whereas ASU and pachymetry could be performed in 530 of 565. Four hundred seventy-nine subjects were statistically assessed after 41 subjects were extracted as outliers from 530 subjects in whom all instruments could be performed. Mean difference between pachymetry and Lenstar was 13.20 ± 13.13 &mgr;m [95% confidence interval (CI): 12.01 to 14.37]. Mean difference between ASU and Lenstar was −0.72 ± 0.35 mm (95% CI: −0.75 to −0.69) for AL, −0.27 ± 0.32 mm (95% CI: −0.30 to −0.24) for ACD, and 0.24 ± 0.28 mm (95% CI: 0.22 to 0.27) for LT. R values were 0.912 (p < 0.001), 0.904 (p < 0.001), 0.487 (p < 0.001), 0.369 (p < 0.001) for CCT, AL, ACD, and LT respectively. Conclusions. AL and ACD were found to be greater with Lenstar, whereas CCT and LT measures were smaller. It is concluded that there was agreement between instruments for CCT and ACD, because the small differences between measures were clinically insignificant. AL and LT values cannot be used interchangeably. If these differences are considered, Lenstar can replace ASU and pachymetry for the majority of children.

The Angle Kappa in Strabismic Individuals

Purpose To determine angle kappa values in strabismic individuals by means of a synoptophore. Methods One hundred-and-eight strabismic subjects and 102 healthy subjects who served as a control group were enrolled in the study. A complete ophthalmologic examination, including determination of refractive status, best-corrected visual acuity measurement, slit-lamp biomicroscopic anterior segment evaluation, intraocular pressure measurements with a Goldmann applanation tonometer, and dilated fundus examination, was done on all study participants. Orthoptic examination included Krimsky prism reflex test, prism cover test, and duction tests. Strabismic patients were grouped into two categories according to their deviation types: exotropic and esotropic. A synoptophore (Clement Clarke, London, England) with a specially designed slide (Maddox test slide series A White Binding No: 16; Clement Clarke, London, England) was used to measure angle kappa. Results Of the 108 strabismic patients, 62 were males and 46 were females with a mean age of 23.38 ± 3.68 years (range: 8 to 82 years). There were 54 males and 48 females with a mean age of 32.74 ± 1.63 years (range: 7 to 68 years) in the control group. The exotropic group had significantly higher angle kappa values than either the controls or the esotropic group (independent sample t-test, p < 0.001). None of the study participants had negative angle kappa values. Higher average kappa values were obtained in left eyes than in right eyes in all three groups (student t-test, p < 0.01 for all groups). Conclusion This study showed that exotropic patients have higher angle kappa values when compared to esotropic patients. Ophthalmologists must take the kappa angle into account when performing a Hirschberg or Krimsky test in young and uncooperative patients in order to improve surgical results.

Long-term follow-up of bilateral botulinum toxin injections versus bilateral recessions of the medial rectus muscles for treatment of infantile esotropia

PURPOSE To compare long-term outcomes of botulinum toxin A injection with incisional surgery for the management of infantile esotropia. SUBJECTS AND METHODS Medical records of infants <24 months treated for esotropia with either botulinum toxin injection (botulinum group) or bilateral medial rectus muscle recessions (surgery group) were reviewed. Minimum follow-up was 48 months, and patients with accommodative esotropia or inferior oblique muscle overaction were excluded. Success was defined as alignment with 10(Δ) of orthophoria without surgery (botulinum group) or without reoperation (surgery group) and compared by the use of an adjusted odds ratio (aOR). RESULTS The record review identified a total of 51 patients, with 25 in the botulinum group and 26 in the surgery group. Median pretreatment deviation was similar in the botulinum and surgery groups (40(Δ) vs 45(Δ); P = 0.37), but median age at treatment was earlier in the botulinum group (10 vs 12.5 months; P = 0.01). The mean number of injections in successfully treated botulinum group patients was 1.4. The success rate was similar in the botulinum (68%) and surgery (77%) groups (aOR = 0.87, P = 0.87). The median follow-up time was longer in the botulinum group (84 vs 75 months; P = 0.02). Gross stereopsis was demonstrable in 10 of 15 patients in the botulinum group and 9 of 13 in the surgery group (aOR = 3.6, P = 0.46). CONCLUSIONS There was no difference in binocular alignment with botulinum toxin versus surgical treatment. Botulinum toxin injection may be considered a primary treatment for infantile esotropia.