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.     

Topographical analysis of corneal astigmatism in patients with tilted-disc syndrome

PURPOSE: To evaluate the corneal topography in patients with tilted-disc syndrome to determine the relationship between optic disc dysversion and corneal astigmatism and the pattern of astigmatism in these patients. METHODS: The study included 23 eyes of the 13 tilted-disc syndrome patients with spheric refractive errors ranging between +1.00 D and -9.00 D (mean -4.00 +/- 3.4 D) and astigmatic errors ranging between -0.50 and -4.50 D (mean -1.95 +/- 0.93 D). Corneal topography was performed by computer-assisted videokeratoscope topographic modelling system 2 (TMS-2) and incidence of corneal astigmatism, corneal topographic patterns, and mean values of the topographic indices were determined. RESULTS: Corneal topographic analysis showed corneal astigmatism in 22 out of 23 patients with tilted discs. Corneal astigmatism was symmetric bow tie pattern in 10 eyes (45.45%), asymmetric bow tie pattern in 11 eyes (50%) and irregular in 1 eye (4.5%). Among the patients with bow tie pattern group (21 eyes), 14 eyes had with-the-rule astigmatism, 1 eye had against-the-rule astigmatism, and 6 eyes had oblique astigmatism. In 18 eyes, astigmatism was corneal, whereas combined corneal and lenticular in 4 eyes and lenticular in 1 eye. CONCLUSION: In the majority of tilted-disc cases, ocular astigmatism is mainly corneal. Morphogenetic factors in the development of the tilted disc might possibly influence the corneal development in such a way to result in corneal astigmatism.     

Morphological study of corneal endothelium and corneal thickness in pseudoexfoliation syndrome

PURPOSE: To examine the endothelial morphology and the central thickness of the cornea in the eyes of patients with pseudoexfoliation syndrome (PXS). METHODS: The corneal endothelium was investigated in 21 patients (26 PXS eyes; 7 eyes of glaucoma patients, and 19 eyes of patients without glaucoma) and in 30 patients with senile cataract or refractive errors who served as the control group (30 non-PXS eyes). The corneal endothelial morphology and central corneal thickness (CCT) were compared between the two groups. RESULTS: The corneal endothelial cell density was significantly lower in the PXS eyes (2336+/-383 cells/mm(2)) than in the non-PXS eyes (2632+/-327 cells/mm(2)) (P=.003). There was no significant difference in the coefficient of variation for the cell area and the percentage of hexagonal cells between these two groups. The central cornea was significantly thinner in the PXS eyes (529+/-31 micro m) than in the non-PXS eyes (547+/-28 micro m) (P=.03). There were no significant differences in these factors between the PXS eyes in patients with and without glaucoma. CONCLUSIONS: In PXS eyes, regardless of the presence of glaucoma in the patients, the corneal endothelial cell density is decreased and the central cornea is thin.     

Changes in central corneal thickness after laser in situ keratomileusis and photorefractive keratectomy

PURPOSE: To evaluate changes in corneal thickness after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) in eyes with the same preoperative refraction, correlate these changes to postoperative refractive outcomes, and compare corneal healing process in a standardized subset of patients. METHODS: Central corneal thickness was measured by contact ultrasound pachymetry in 14 eyes of 8 patients with preoperative myopia of -6.00 D who had LASIK, and in 14 eyes of 8 patients with the same preoperative refractive error who had PRK. Measurements were taken preoperatively, and 1 week, 3, and 6 months after surgery. Data were evaluated and compared using the paired Student t-test and Pearson correlation coefficient. RESULTS: Mean preoperative central corneal thickness in the LASIK group was 549.14 +/- 37.4 microm, and in the PRK group, 552.64 +/- 34.9 microm. At 1-week postoperatively, mean central corneal thickness in the LASIK eyes was 467.28 +/- 29 microm and in the PRK eyes, 473.85 +/- 39.2 microm; at 6 months, central corneal thickness had increased in both groups compared to the 1-week values; LASIK eyes had a mean central corneal thickness of 481.42 +/- 23.0 microm and PRK, 481.50 +/- 35.3 microm. Mean postoperative refraction after 6 months was -0.48 +/- 0.30 D in the LASIK group and -0.67 +/- 0.35 D in the PRK group. CONCLUSION: Increase in central corneal thickness between 1 week and 6 months postoperatively occurred in both LASIK and PRK eyes, but differences were not statistically significant. No statistically significant differences were found in myopic regression between the two patient groups.     

Central corneal thickness correlated with glaucoma damage and rate of progression

PURPOSE: To evaluate whether the amount of glaucomatous optic nerve damage at presentation of the patient and the rate of progression of glaucoma during follow-up are related to central corneal thickness. METHODS: The prospective observational clinical study included 861 eyes of 454 white subjects (239 normal eyes of 121 subjects, 250 ocular hypertensive eyes of 118 patients, 372 eyes of 215 patients with chronic open-angle glaucoma). For 567 eyes (304 patients) with ocular hypertension or chronic open-angle glaucoma, follow-up examinations were performed, with a mean follow-up time of 62.7 +/- 33.2 months (median, 60.8; range, 6.2-124.9). All patients underwent qualitative and morphometric evaluation of color stereo optic disc photographs and white-on-white visual field examination. Central corneal thickness was measured by corneal pachymetry. RESULTS: Central corneal thickness correlated significantly (P < 0.001) and positively with the area of the neuroretinal rim and negatively with the loss of visual field. Development or progression of glaucomatous visual field defects detected in 119 (21.0%) eyes was statistically independent of central corneal thickness, in univariate (P = 0.99) and multivariate Cox regression analyses (P = 0.19). CONCLUSIONS: At the time of patient referral, the amount of glaucomatous optic nerve damage correlated significantly with a thin central cornea. Progression of glaucomatous optic nerve neuropathy was independent of central corneal thickness, suggesting that central corneal thickness may not play a major role in the pathogenesis of progressive glaucomatous optic nerve damage.     

Central corneal thickness and thickness of the lamina cribrosa in human eyes

PURPOSE: Since central corneal thickness may inversely influence the amount and rate of progression of glaucomatous optic nerve damage and because lamina cribrosa thickness may be of importance in susceptibility to glaucoma, it was the purpose of the present study to evaluate whether central corneal thickness is related to lamina cribrosa thickness. METHODS: The histomorphometric study included 111 enucleated nonglaucomatous eyes of 111 white subjects. On anterior-posterior histologic sections through the pupil and the central optic disc region, the thickness of the cornea, lamina cribrosa, and peripapillary sclera and the shortest distance between the intraocular space and the cerebrospinal fluid space were measured. Axial length ranged between 20 and 32 mm. RESULTS: Mean central corneal thickness (mean +/- SD: 616.6 +/- 108.3 microm) and mean central lamina cribrosa thickness (378.1 +/- 117.8 microm) were statistically independent of each other (P = 0.15; correlation coefficient, r = 0.14). In a similar manner, lamina cribrosa thickness at the optic disc border was statistically independent of central corneal thickness (P = 0.51; r = 0.06) and peripheral corneal thickness (P = 0.34; r = 0.09). In a parallel way, peripapillary scleral thickness (P = 0.84) and the shortest distance between the prelaminar space and cerebrospinal fluid space (P = 0.10) were statistically independent of central corneal thickness. CONCLUSIONS: In nonglaucomatous human globes, central corneal thickness may not correlate significantly with lamina cribrosa thickness, peripapillary scleral thickness, and shortest distance between intraocular space and cerebrospinal fluid space. Histologic artifact and sectioning methods could partially account for the lack of an association. The study results may suggest clinically that an assumed relationship between central corneal thickness and susceptibility to glaucoma cannot be explained by an anatomic correspondence between corneal thickness and histomorphometry of the optic nerve head.     

Corneal changes and wavefront analysis after orthokeratology fitting test

PURPOSE: To evaluate corneal changes and ocular aberrations during an orthokeratology test. DESIGN: A prospective, nonrandomized cohort study. METHODS: Fourteen myopic patients (26 eyes) underwent an orthokeratology fitting test with the BE contact lens (Ultravision Pty, Ltd, Brisbane, Australia). Best spectacle-corrected visual acuity (BSCVA), uncorrected (Ultravision Pty, Ltd, Brisbane, Australia) visual acuity (UCVA), subjective cycloplegic refraction, biomicroscopy, corneal topography, optical pachymetry, and aberrometry were performed at baseline and one and eight nights orthokeratology. The short-term effect of orthokeratology using corneal topography, tomography, and ocular aberrations was evaluated. RESULTS: The mean spherical equivalent changed from -2.24 +/- 0.98 diopters (D) at baseline to 0.15 +/- 0.76 D after the eight nights of lens wear (P = .001). All patients had an UCVA of 20/30, 69.2% with 20/20. Changes in central corneal pachymetry were not observed. There was a statistically significant increase in the temporal corneal thickness from night one, without any difference between nights one and eight (P > .001). A significant increase of higher-order root mean square values was observed from baseline (0.42 +/- 0.16 mum), night one (0.81 +/- 0.24 mum), and night eight (1.04 +/- 0.24 mum). Increases in coma (Z7+Z8) and spherical aberration (Z12) were observed. Positive horizontal (Z8) coma increased in right eyes, and negative horizontal (Z8) coma increased in left eyes (P < .001). CONCLUSIONS: Myopia reduction resulting from rapid central corneal flattening and improvement of UCVA occurred after orthokeratology. Higher-order aberrations (HOAs), particularly spherical aberration and coma, increased significantly during the orthokeratology test. An increase of temporal pachymetry and differences in coma direction induced between the eyes may be related to the subclinical lens decentration temporally.     

Corneal flap thickness in laser in situ keratomileusis using the summit Krumeich-Barraquer microkeratome

PURPOSE: To evaluate the thickness of corneal flaps created by the Summit Krumeich-Barraquer microkeratome (SKBM) (Alcon Surgical) and identify factors that may influence flap thickness. SETTING: SSK Ankara Eye Hospital, Ankara, Turkey. METHODS: Seventy-eight eyes of 50 patients who had laser in situ keratomileusis with the Asclepion-Meditec MEL 70 G-Scan excimer laser and the SKBM were prospectively evaluated. Preoperatively, the central corneal thickness, keratometry, visual acuity, and manifest refraction were measured. The microkeratome with the suction ring designed to create 160 microm thick and 9.0 to 9.5 mm diameter flaps was used in all eyes. Stromal bed thickness was measured with the Pachette ultrasonic pachymeter (DGH Technology, Inc.) after the flap was lifted. Flap thickness was calculated by subtracting the central stromal bed thickness from the preoperative central corneal thickness. RESULTS: The mean preoperative central corneal thickness was 546.7 microm +/- 31.9 (SD), the mean manifest refraction spherical equivalent was -6.8 +/- 3.4 diopters (D), and the mean corneal refractive power was 42.9 +/- 1.5 D. The mean corneal flap thickness created by the microkeratome was 154.9 +/- 19.3 microm (range 101 to 202 microm). There was no correlation between corneal flap thickness and the degree of myopia (P =.151) or the corneal refractive power (P =.257). There was a linear relationship between flap thickness and the preoperative central corneal thickness (P =.000). A posterior corneal stroma thicker than 250 microm was preserved in 87 eyes (98.9%). CONCLUSIONS: The SKBM produced corneal flaps that were consistently close to the intended thickness. Corneal flap thickness did not appear to be influenced by the degree of myopia or the corneal refractive power; however, there was a linear relationship between flap thickness and the preoperative central corneal thickness.     

Cataract surgery for congenital cataract: endothelial cell characteristics, corneal thickness, and impact on intraocular pressure.

PURPOSE: To investigate whether central corneal thickness (CCT), endothelial cell characteristics, and intraocular pressure (IOP) are affected in patients with previous congenital cataract surgery and to focus on their clinical significance. METHODS: CCT and IOP measurements and specular microscopy were performed in 31 eyes of 17 cases of extracted congenital cataracts and 40 eyes of 20 age- and sex-matched participants as control group. The mean of three pachymetry measurements of the central cornea was taken as CCT. IOP was checked using an applanation tonometer. RESULTS: The mean corneal thickness of the eyes with extracted congenital cataract (632+/-45 microm) was significantly greater than that of the control eyes (546+/-33 microm; p<0.001). There was no significant difference in the corneal endothelial cell count, coefficient of variation (CV), and mean cell area (AVG) of endothelial cells between operated eyes and the control group. The mean measured IOP in the operated group (22.8+/-3.3 mm Hg) was significantly greater than IOP in controls (14.1+/-1.8 mm Hg, p<0.001). CONCLUSIONS: Although the corneas were clinically clear and there was no significant difference in endothelial characteristics of eyes with extracted congenital cataract and controls, central corneas of operated eyes were significantly thicker than those of controls. To differentiate the actual glaucoma from ocular hypertension in these patients, the central corneal thickness measurement should strongly be considered.     

In vivo femtosecond laser-assisted posterior lamellar keratoplasty in rabbits

PURPOSE: To develop a rabbit model for femtosecond laser-assisted posterior lamellar keratoplasty. METHODS: The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 12 eyes of 11 rabbits. Laser parameters were energy 6.0 to 8.7 (lamellar cut) and 6.0 to 8.8 microJ (trephination cut), spot size 2.4 microm, firing rate 15 kHz, and trephination diameter 6.0 to 7.0 mm. In all eyes, the posterior corneal disc was removed from the eye after laser treatment through a blade incision in the peripheral cornea. The same excised corneal disc was repositioned into the posterior stromal bed to simulate posterior lamellar transplantation. Four eyes of 3 rabbits were enucleated immediately after surgery, and 8 eyes of 8 rabbits were enucleated after a mean follow-up of 17.9 +/- 6.5 weeks. The corneal cut surfaces were examined by light microscopy and scanning electron microscopy. RESULTS: The femtosecond laser was successful in producing posterior lamellar and trephination cuts in rabbit eyes. The thickness of the posterior corneal discs was 204.3 +/- 21 microm (56.9% of central corneal thickness), and postoperative keratometry was 49.1 +/- 5.8 D. Clinical appearance consistent with corneal ectasia was noted in 3 eyes. CONCLUSION: The femtosecond laser can make nonmechanical cuts for posterior lamellar keratoplasty with relative ease and reliability in rabbit eyes. A minimum residual anterior corneal thickness may need to be maintained to prevent ectasia.     

Morphology of corneal nerves and corneal sensation in dry eye: a preliminary study

PURPOSE: To evaluate the corneal sensitivity and nerve morphology in dry eyes. METHODS: A total of 32 eyes of 16 patients (10 Sjogren's syndrome and six non-Sjogren's syndrome) and 19 eyes of 10 age-matched controls were studied. Sensitivity of the central cornea was measured by the Cochet-Bonnet aesthesiometer. The morphology of corneal nerves was studied by in vivo confocal microscopy (ConfoScan 2.0, Fortune Technologies Srl, Vigonza (PD), Italy). Sub-basal epithelial nerve plexus, subepithelial nerve plexus, and stromal nerves were localized and evaluated for the number of nerves, thickness, reflectivity, and tortuosity for each frame. RESULTS: The mean corneal sensitivity of dry eye patients (5.6 mm/grs/S) was found significantly lower than that of the control (5.0 mm/grs/S) group (P<0.01). Although the subepithelial nerves were thicker in dry eyes (mean: 6.38+/-1.18 microm) than control eyes (mean: 5.72+/-1.27 microm), this difference was not significant (P>0.05). CONCLUSION: Decreased corneal sensitivity is not associated with morphological changes of corneal nerves in dry eyes.     

Iris colour, optic disc dimensions, degree and progression of glaucomatous optic nerve damage

PURPOSE: To evaluate whether iris colour influences size and shape of the optic nerve head and risk for glaucoma progression. METHODS: The hospital-based observational study included 1973 eyes of 1012 Caucasian subjects with ocular hypertension or chronic open-angle glaucoma. For all patients, colour stereo optic disc photographs were evaluated, and corneal pachymetry and achromatic perimetry were performed. Main outcome measures were optic nerve head parameters, the development or progression of visual field defects and iris colour. RESULTS: In most of the study groups, size of the optic disc, neuroretinal rim, alpha zone and beta zone of parapapillary atrophy, retinal vessel diameter and central corneal thickness did not differ significantly between eyes with blue, green, brown and mixed iris colour. In the normal-pressure glaucoma group, neuroretinal rim area was smallest in the population with mixed-coloured eyes and largest in the group of eyes with brown irides (P = 0.001 after correction for inter-eye dependency and multiple testing). For the ocular hypertensive subjects and glaucoma patients with follow-up examinations, the rate of development or progression of glaucomatous visual field loss was not significantly associated with iris colour (P = 0.060). CONCLUSIONS: In Caucasian subjects, iris colour does not have a major association with the size of the optic nerve head structures, central corneal thickness and retinal arterial diameter. In Caucasian patients with ocular hypertension or chronic open-angle glaucoma, an influence of iris colour on the risk for development or progression of glaucomatous visual field defects could not be confirmed.     

Corneal flap dimensions in laser in situ keratomileusis using the Innovatome automatic microkeratome

To evaluate the thickness and size consistency of the corneal flap created with the Innovatome automatic microkeratome and to determine any correlation between preoperative variables and these corneal flap dimensions, we performed a prospective study comprising of 268 eyes of 143 patients having laser in situ keratomileusis. Either No. 170 or No. 190 blade was used, and preoperative variables including the central corneal thickness, keratometry (K) reading, spherical equivalent, and the blade type were measured. The mean central corneal flap thickness was 138.8 +/- 23.5 microns (range, 71.6-193.7 microns) in blade 170 group, and 148.3 +/- 25.4 microns (range, 80.3-211.7 microns) in blade 190 group. No relationship was found between the corneal flap thickness and the preoperative K reading or the spherical equivalent, but the corneal flap thickness increased with the preoperative central corneal thickness. The mean vertical flap diameter was 9.18 +/- 0.25 mm (range, 8.50-9.75 mm) in blade 170 group, and 9.50 +/- 0.31 mm (range, 8.75-10.00 mm) in blade 190 group. No relationship was found between the corneal flap diameter and the preoperative central corneal thickness or the spherical equivalent, but the corneal flap size increased with the preoperative K reading.     

Central and peripheral corneal pachymetry--standard evaluation with the Pentacam system

BACKGROUND: Corneal thickness measurements are important in refractive surgery, for interpretation of IOP and in corneal diseases. The purpose of this study was to generate specific standard values for the Pentacam system and to investigate the influence of body size, body mass index, body weight, gender and refraction on central and peripheral corneal thickness for a more detailed characterization of the corneal anatomy. MATERIALS AND METHODS: The Pentacam system is based on a 180 degrees rotating computer-aided Scheimpflug camera, which generates reconstructions of the anterior segment from 12 to 50 single captures. The central corneal thickness was calculated from 25 single captures in both eyes of 182 normal Caucasian subjects (age: 18 - 83 years). The peripheral corneal thickness was measured within 3 mm distances at 0 degrees , 90 degrees , 180 degrees and 270 degrees . All subjects underwent an ophthalmological examination. Correlations between corneal thickness and body size, body mass index, body weight, gender and refraction were analyzed statistically by non-parametric tests. RESULTS: The mean central corneal thickness of all 364 eyes was 534 +/- 36 microm. Divided into sides it was the same, 534 +/- 36 microm, in the right and in the left eyes. The mean central corneal thickness for female subjects was 533 +/- 40 microm, for males it was 534 +/- 35 microm. Statistically there was no proof of any dependence of the central corneal thickness values on the sides, gender, age, height, body mass index (BMI) or refraction. However, there was a positive significant correlation between central corneal thickness and body weight. The peripheral corneal thickness values were lowest in the temporal and inferior areas and greatest in the superior and in the nasal areas. In the superior and in the nasal areas there was a statistically significant negative correlation between age and peripheral corneal thickness. CONCLUSIONS: The corneal thickness can be measured touchless with the Pentacam system. The central corneal thickness seems to be correlated with the body weight. Anatomical features lead to lower peripheral corneal thickness values in the temporal and inferior areas than in the nasal and superior areas. In the nasal and in the superior areas the corneal thickness seems to decrease with age. Further trials are necessary to confirm these findings and to evaluate the precision, reproducibilitiy and independence of investigators of the corneal pachymetry with the Pentacam system.     

Longitudinal changes in central corneal thickness and their relation to glaucoma status: an 8 year follow up study

AIMS: To determine if central corneal thickness (CCT) changes over time and if this change relates to glaucoma progression. METHODS: 39 patients (64 eyes) with open angle glaucoma, ocular hypertension, glaucoma suspect status, or a normal eye examination were examined at two visits. CCT, age, race, sex, family history of glaucoma, presence of diabetes and systemic hypertension, diagnosis, visual acuity, spherical equivalent, intraocular pressure, vertical and horizontal cup to disc ratios, number of glaucoma medications prescribed, Advanced Glaucoma Intervention Study (AGIS) score and mean deviation of Humphrey visual fields, and interventions required were recorded. Statistical analysis used the Wilcoxon signed ranks test, linear regression, and analysis of variance. RESULTS: Between the two visits (mean 8.2 years apart), mean CCT decreased by 17 mum in right eyes (p<0.002) and by 23 mum in left eyes (p<0.001). This decrease was greater in right eyes of patients with primary open angle glaucoma than in normals (p = 0.041). There was no significant association between change in CCT and other examination parameters. Change in CCT was not associated with topical carbonic anhydrase inhibitor use. CONCLUSION: In this longitudinal study, CCT decreased over time, but this may not be related to glaucoma progression.     

Central corneal thickness in patients with Weill-Marchesani syndrome

PURPOSE: To investigate whether central corneal thickness (CCT) is affected in patients with Weill-Marchesani syndrome (WMS) and to focus on its clinical significance. DESIGN: Case-control study. METHODS: Complete ocular examination was performed in case and control groups, and then the lowest reading of ten pachymetry measurements of the central cornea was taken as CCT. RESULTS: All participants, case and controls, were female and age matched (P = .7). The mean of central corneal thickness in twelve eyes of six patients with WMS was thicker (631.5 +/- 25.9 microns) than 40 eyes of 20 normal persons (535.8 +/- 25.9 microns) in the control group (P < .0001). CONCLUSIONS: Increased CCT seems to be a previously unrecognized aspect of WMS. This may lead to overestimation of intraocular pressure by applanation tonometers. Therefore, unusually thick CCT should be considered in interpreting the Goldmann tonometric reading in diagnosis and management of glaucoma in this rare syndrome.     

Tilted disc syndrome: an OCT and mfERG study

Purpose To evaluate retinal thickness and function in eyes with tilted disc syndrome with optical coherence tomography (OCT) and multifocal electroretinogram (mfERG). Methods Twenty-one eyes of 12 patients (4 males and 8 females) with tilted disc were studied with OCT3 and mfERG and compared with 40 eyes of 20 age and sex-matched control subjects. The thickness of the fovea and the thickness of retinal nerve fibre layer (RNFL) along a 3.4-mm-diameter circle centred on the optic nerve head were evaluated using OCT3. The macular cone function was tested by mfERG. Results The OCT-derived RNFL thickness was significantly decreased in the superior area of eyes with tilted disc with a mean value equal to 106.47 μm (SD 24.1). The mean response amplitude density of the fovea (11.75 nV/deg2) and parafovea (8.22 nV/deg2) was significantly lower in eyes with tilted disc than in normal eyes. Conclusion OCT and mfERG can be objective tools for assessing anatomical and functional damage of the macula. Our results suggest that in tilted disc syndrome even without visual impairment the optic nerve and the macula show dysfunction not visible by other means.     

Optic disc area in different types of glaucoma

AIM: To evaluate the possible relationship of optic disc area with retina nerve fiber layer in different glaucoma subtypes. METHODS: One eye each was chosen from 45 patients with ocular hypertension, 45 patients with primary open angle glaucoma, 45 patients with pseudoexfoliation glaucoma and 45 healthy controls followed in our hospital. The records of the patients were reviewed retrospectively. Optic disc area and circumpapillary retina nerve fiber layer measurements were obtained using optical coherence tomography. Central corneal thickness was measured by ultrasound pachymetry. RESULTS: The median disc area in the patients with primary open angle glaucoma was significantly higher than the patients with ocular hypertension (2.19 vs 1.90 mm2, P=0.030). The median retina nerve fiber layer was thinner in the patients with primary open angle glaucoma and pseudoexfoliation glaucoma than the patients with ocular hypertension for superior, inferior and temporal quadrants. After adjustment for age, no difference in central corneal thickness was found between the groups. Greater disc area was associated with thicker retinal nerve fiber layer for superior, inferior and nasal quadrants in the patients with primary open angle glaucoma. There was no correlation between disc area and central corneal thickness measurements of the groups. CONCLUSION: Disc size affects the retinal nerve fiber layer thickness in eyes with primary open angle glaucoma and is a possible risk factor for glaucomatous optic nerve damage.     

Evaluation of central corneal thickness in children and adolescents with type I diabetes mellitus

PURPOSE: To evaluate corneal thickness in diabetic and nondiabetic patients. MATERIALS AND METHODS: The central corneal thickness (CCT) was investigated in 100 eyes of 100 patients with diabetes type I and in 99 nondiabetic patients (99 eyes). The mean diabetic patients age was 15.31 +/- 3.18 years. The mean age in control group was 14.3 +/- 2.2 years. Corneal thickness was measured by non-contact microscope Topcon SP-2000P Statistical analysis was performed to assess systemic factors (patient age, sex, duration of diabetes mellitus, hemoglobin A1c value, diabetes control) related to CCT. SAS STAT (Release 8.2) program, the independent t-test, Kolmogorow-Smirnow test and Bartlett test were used to compare differences between the diabetic and control group. RESULTS: In our study the mean CCT in diabetic eyes was 0.54 +/- 0.03 mm and was significantly increased, compared to control group (0.525 +/- 0.037 mm). None of systemic factors was correlated with CCT. CONCLUSIONS: Our findings indicate that diabetes mellitus affects thickness of cornea in adolescents. Evaluation of endothelium in specular microscope should be performed in the diabetic patients.     

Central corneal thickness and corneal diameter in patients with childhood glaucoma

PURPOSE: To determine and compare the central corneal thickness (CCT) and corneal diameter among groups of patients with childhood glaucomas and assess the relationship between CCT and corneal diameter in these patients. DESIGN: A multicenter observational case series using prospective and retrospective data. METHODS: Patients from the Scheie Eye Institute, Children's Hospital of Philadelphia, and Emory and Vanderbilt Medical Centers with childhood glaucomas were eligible to participate. Retrospective data on CCT and corneal diameter of these patients were collected when available; otherwise, patients were asked to return to the ophthalmology clinics for measurements. Patients with corneal edema or central corneal scarring were excluded. One hundred eighty four glaucomatous eyes from 109 patients (median age = 9.0 y; age range = 0 to 60 y) were included. RESULTS: The mean CCT (+/-SE) was 651.1+/-63.5 microm for aphakic, 528.7+/-38.5 microm for Axenfeld-Rieger, and 563.4+/-67.9 microm for 1 degrees infantile eyes. The mean corneal diameter in aphakic, Axenfeld-Rieger, and 1 degrees infantile glaucoma eyes were 11.2+/-1.0, 12.5+/-0.9, and 13.2+/-1.2 mm, respectively. There was a significant difference in CCT and in corneal diameter between aphakic and 1 degrees infantile glaucoma eyes, and between aphakic and Axenfeld-Rieger eyes (P < 0.0001). There was a negative correlation between CCT and corneal diameter in all eyes (r = -0.41, P < 0.0001). CONCLUSIONS: Patients with aphakic glaucoma are different from those with congenital glaucoma or Axenfeld-Rieger in CCT and corneal diameter. A patient with pediatric glaucoma and a larger corneal diameter was more likely to have a thinner CCT. Attention should be paid to the CCT of patients with childhood glaucomas for interpretation of intraocular pressure.