The complementary benefit of anterior segment optical coherence tomography in penetrating keratoplasty.

PURPOSE: To evaluate the utility of anterior segment optical coherence tomography (AS-OCT) assessment in the pre- and postsurgical management of full-thickness corneal grafts. METHODS: Seventy eyes of 58 patients who had penetrating keratoplasty were included in the study. High resolution AS-OCT scans of the cornea and the anterior segment were performed before and after transplantation in 17 eyes with the Visante™ optical coherence tomography. Fifty-three eyes were examined in the late postoperative period. RESULTS: The mean follow-up was 4.3 years (range, 1-15 years). Six different graft-host junctions were identified. Three patients with graft rejection, four patients with anterior synechia, and three patients with corneal ulcer were evaluated. Preoperative evaluation of eyes with semiopaque and totally opaque corneas revealed important information about anterior segment structures additional to slit-lamp findings. CONCLUSION: AS-OCT is a useful complementary tool for the evaluation of penetrating corneal transplantation surgery and in the management of its postoperative complications.

Assessment of intrastromal corneal ring segment position with anterior segment optical coherence tomography.

BACKGROUND AND OBJECTIVE: To examine the exact position of implanted Keraring (Mediphacos, Belo Horizonte, Brazil) segments by high-resolution anterior segment optical coherence tomography (AS-OCT). PATIENTS AND METHODS: This study included 17 eyes of 13 patients with keratoconus who underwent uneventful intracorneal ring segment implantation with the aid of femtosecond laser. Eyes were evaluated by AS-OCT at the third postoperative month. Distance from the apex of the triangular cross-section of the ring segment to the anterior corneal surface and distances from two basal corners to the posterior corneal surface were measured. RESULTS: Distance from apex to anterior corneal surface (263.1 ± 42.9 µm) was significantly smaller than target depth calculated intraoperatively (356.9 ± 35.7 µm, P < .001). Distance between outer basal corner and posterior corneal surface was significantly greater than distance between inner basal corner and posterior corneal surface. CONCLUSION: High-resolution AS-OCT is a rapid, convenient, and valuable technique in the follow-up of patients with implanted Keraring segments that may be helpful in predicting ring-related complications.

Short-term effects of a single intravitreal bevacizumab injection on retinal vessel calibre.

PURPOSE: The aim was to investigate the short-term effects of a single intravitreal bevacizumab injection on the retinal vessel calibre in patients with neovascular age-related macular degeneration and in patients with diabetic macular oedema. METHODS: Twelve patients with neovascular age-related macular degeneration and eight patients with diabetic macular oedema were included in the study. All patients received an intravitreal injection of 1.25 mg bevacizumab. Red-free fundus photographs (35°) were acquired with a fundus camera at baseline and one day, one week and one month after the intravitreal injection. Measurements of retinal vessel diameter were made of the supero-temporal retinal venule and arteriole using the software available on the IMAGEnet program. RESULTS: Although there appeared to be a trend towards vasoconstriction for the measurements in the diabetic macular oedema group (both for arterioles and venules at day 7) and the age-related macular degeneration group (for venules at day 1 and for arterioles at day 7), it did not reach statistical significance (p > 0.05). Optical coherence tomography revealed a significant decrease in foveal thickness measurements in both groups at the one month visit compared with baseline. CONCLUSION: The results suggest that intravitreal injection of bevacizumab might induce retinal vasoconstriction; however, low numbers of subjects might have prevented the difference from reaching statistical significance. Further studies with a larger number of subjects would reveal the effect of intravitreal anti-vascular endothelial growth factor treatment on retinal vessel diameters more clearly.

Intraoperative use of AS-OCT during intrastromal corneal ring segment implantation.

BACKGROUND AND OBJECTIVE: To evaluate femtosecond laser-created tunnels intraoperatively by anterior segment optical coherence tomography (AS-OCT) during intrastromal corneal ring segment implantation. PATIENTS AND METHODS: The study prospectively examined 13 eyes of 11 patients who underwent intrastromal corneal ring segment surgery with the aid of femtosecond laser. All eyes had keratoconus as the primary diagnosis. Eyes were examined by AS-OCT to image the tunnel immediately after femtosecond laser and before ring segment implantation. Tunnel depth was calculated automatically using the software's flap tool and calipers. RESULTS: The presence of air bubbles demonstrated the tunnel successfully by AS-OCT. Tunnel depth was measured at eight locations in four cross-sections of high-resolution cornea images. An overall evaluation was also made by changing the scan direction 360°. After confirmation that a uniform tunnel was satisfactorily created at the aimed depth, surgery proceeded with segment implantation. CONCLUSION: AS-OCT can be used intraoperatively to assess femtosecond laser-created tunnel in intrastromal corneal ring segment implantation. The qualitative and quantitative evaluation of the intrastromal tunnel by AS-OCT before implantation of the ring segments is a practical intraoperative approach that may offer a safer surgery.

Comparison of non-contact methods for the measurement of central corneal thickness.

BACKGROUND AND OBJECTIVE: This study examined the repeatability of and agreements between central corneal thickness measurements obtained by four different non-contact pachymetry devices. PATIENTS AND METHODS: Seventy-eight eyes of 39 subjects were included. Central corneal thickness of each eye was measured by Visante optical coherence tomography (OCT) (Carl Zeiss Meditec Inc., Dublin, CA), Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany), Orbscan IIz topography (Bausch & Lomb Surgical Inc., San Dimas, CA), and slit-lamp OCT (SL-OCT) (Heidelberg Engineering GmbH, Heidelberg, Germany). Inter-device agreements and correlations and repeatability of each device were examined. RESULTS: All measurement methods correlated well with each other with a correlation coefficient greater than 0.90 and P value of less than .001 for all comparisons. However, Pentacam overestimated central corneal thickness: 546.7 ± 38.2, 535.5 ± 42.7, 531.7 ± 37.6, and 531.2 ± 36.0 µm for Pentacam, Orbscan IIz, Visante OCT, and SL-OCT, respectively (P < .001 for all comparisons versus Pentacam). Despite good correlation, magnitude of differences was high and this bias was proportional (ie, not constant across a range of corneal thickness values) for the following pairs: Orbscan versus Visante OCT, Orbscan versus SL-OCT, and Orbscan versus Pentacam (P < .001 for all comparisons). CONCLUSION: Although measurements obtained by various non-contact methods correlate well, numerical agreement of the results may not be sufficient for their interchangeable use in clinical practice.

Corneal biomechanical properties of patients with pseudoexfoliation syndrome.

PURPOSE: To assess the corneal biomechanical properties of patients with pseudoexfoliation syndrome (PEX syndrome). METHODS: Fifty-two eyes of 52 patients (27 unilateral and 25 bilateral) and 42 eyes of 42 age-matched control subjects were enrolled in the study. Metrics of corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with the ocular response analyzer (ORA). The ORA also determined the values of Goldmann-correlated intraocular pressure and corneal-compensated intraocular pressure. Central corneal thickness (CCT) was measured by the ORA integrated handheld ultrasonic pachymeter. The values recorded by the ORA were compared between eyes with PEX syndrome and those without PEX syndrome. Eyes with unilateral PEX syndrome and fellow eyes without PEX syndrome were also compared. RESULTS: The mean CH and CRF of all eyes with PEX syndrome were significantly lower than those of control eyes (P < 0.05). Neither corneal-compensated intraocular pressure nor Goldmann-correlated intraocular pressure showed a statistically significant difference in both the groups. Mean CCT values also did not show significant difference. Comparison of the unilateral eyes with PEX syndrome with the apparently normal fellow eyes revealed no significant difference between the mean CCT, mean CH, and mean CRF values (P > 0.05). However, the mean corneal-compensated intraocular pressure and Goldmann-correlated intraocular pressure were relatively higher in the PEX syndrome eye (P < 0.05). There was no significant difference between the mean CCT values of these groups (P > 0.05). CONCLUSIONS: The CH and CRF decrease in both unilateral and bilateral PEX syndrome suggested that PEX syndrome has a weakening effect on corneal biomechanical properties. Moreover, in subjects with clinically unilateral PEX syndrome, these properties were closer to eyes with PEX syndrome than to normal control eyes.

Influence of intrastromal corneal ring segment implantation on corneal biomechanical parameters in keratoconic eyes.

PURPOSE: To assess the influence of intrastromal corneal ring segment (ICRS) implantation on corneal biomechanics in patients with keratoconus. METHODS: Patients with keratoconus who underwent femtosecond laser-assisted ICRS (Keraring) implantation were evaluated with the ocular response analyzer (ORA). Metrics of corneal biomechanical parameters, including corneal hysteresis (CH) and corneal resistance factor (CRF) were measured both before and after surgery. The postoperative measurements recorded at the 1st, 3rd and 6th months, and 1st and 2nd years after surgery were analyzed. RESULTS: The mean CRF was significantly lower in the early postoperative period (1st and 3rd month); however, the difference between the mean preoperative and late postoperative (6th months, 1st and 2nd years) CRF values was not significant. There were no significant differences between the mean preoperative and postoperative CH values. CONCLUSIONS: In the early postoperative period a significant temporary decrease in CRF was observed after the femtosecond laser-assisted ICRS implantation; however, this surgery did not alter the CH significantly in the same time interval. Both CH and CRF did not show significant alteration from preoperative values in the late postoperative period.

Fundus autofluorescence in acute and chronic central serous chorioretinopathy.

BACKGROUND: A prospective evaluation of the pattern of fundus autofluorescence in cases of acute versus chronic central serous chorioretinopathy (CSR). METHODS: A prospective, cross-sectional, single-centre investigation was performed using three diagnostic techniques, namely, fundus autofluorescence, optical coherence tomography and fundus fluorescein angiography to evaluate a sample of patients (n = 42 eyes) with both acute (n = 25 eyes) and chronic (n = 17 eyes) CSR. RESULTS: Hypoautofluoresecence was found in 80 per cent (20 eyes) and 88.2 per cent (15 eyes) of eyes in the acute and chronic central serous chorioretinopathy groups, respectively, corresponding to the leakage points depicted by fluorescein angiography. Hypoautofluoresence corresponding to the areas of subretinal fluid accumulation was seen in 92 per cent (23 eyes) and 82.3 per cent (14 eyes) of the acute and chronic central serous chorioretinopathy groups, respectively. In two eyes (11.6 per cent) with chronic CSR, hyperautofluorescent changes were noted at the previous leakage points. In the acute CSR group, speckled hyperautofluorescence was detected in nine eyes (36 per cent) after the resolution of subretinal fluid. In the chronic CSR group, simultaneous speckled hyperautofluorescence was detected in the previous areas of subretinal fluid accumulation in 12 eyes (70.5 per cent). CONCLUSION: Fundus autofluorescence imaging delineates endogenous fluorescence derived mainly from lipofuscin within the retinal pigment epithelium (RPE) layer and therefore permits evaluation of functional alterations in the RPE in numerous retinal diseases. Data from fundus autofluorescence revealed distinctive findings in acute and chronic CSR. Fundus autofluorescence imaging may be used as a supplementary diagnostic tool for identifying patients with CSR and differentiation may be made between acute and chronic cases.

Glutathione S-transferase M1, GSTT1 and GSTP1 genetic polymorphisms and the risk of age-related macular degeneration.

PURPOSE: To determine the possible effects of glutathione S-transferase (GST) M1, GSTT1 and GSTP1 genetic polymorphisms on the risk of developing age-related macular degeneration (AMD). PATIENTS AND METHODS: This case-control study included a total of 120 patients with AMD (65 with dry-type AMD and 55 with wet-type AMD) and 198 disease-free controls. GSTM1 and GSTT1 polymorphisms were analyzed by using a multiplex polymerase chain reaction (PCR), and GSTP1 polymorphism was detected by real-time PCR assay. RESULTS: GSTM1-null genotype was significantly associated with the development of AMD (p = 0.01, OR = 1.82, 95% CI = 1.14-2.91). Stratification by AMD subtypes revealed a significant relationship between GSTM1-null genotype and dry-type AMD (p = 0.02, OR = 1.98, 95% CI = 1.10-3.53). In a stepwise regression model, only GSTM1-null genotype was significantly associated with the development of AMD (p = 0.01, OR = 1.77, 95% CI = 1.11-2.81). CONCLUSIONS: Our findings suggest that genetic polymorphisms of GST may have a role in the development of AMD.

AS-OCT as a tool for flap thickness measurement after femtosecond-assisted LASIK.

BACKGROUND AND OBJECTIVE: to investigate the efficacy of anterior segment optical coherence tomography (AS-OCT) for calculating flap thickness in femtosecond laser-assisted laser in situ keratomileusis. PATIENTS AND METHODS: fifty-one eyes of 26 patients with myopia and myopic astigmatism were included in this prospective study. High-resolution corneal images were evaluated at 1 week and 1 month postoperatively. Images along the horizontal meridian were measured with the flap tool at seven points. RESULT: measurements at vertex and at 1 mm nasally and temporally from the vertex were indistinct but easily defined. Although statistically not significant, flaps were found to be thinner in the central cornea and thicker in the periphery (P > .05). CONCLUSION: AS-OCT provides detailed high-resolution images for quantitative evaluation of the flap-stroma relationship, but it may not be precise in the central 2-mm area of the cornea. Despite this, AS-OCT is an imaging tool with significant utility.

Anterior segment optical coherence tomography findings of acute hydrops in a patient with keratoconus.

The authors describe the anterior segment optical coherence tomography (AS-OCT) findings of a 25-year-old patient with acute hydrops associated with keratoconus. The patient presented with decreased visual acuity, pain, and redness in the left eye. The symptoms, clinical presentation, and topographical findings of the right eye confirmed this condition to be acute corneal hydrops. The patient was closely followed up with hyper-osmotic (NaCl 5%) and nonsteroidal anti-inflammatory (ketorolac tromethamine 0.5%) topical treatment. At the initial examination and during follow-up, the evaluation of the anterior segment was performed using optical coherence tomography. Changes in the stroma and Descemet's membrane during the healing process of acute hydrops could be demonstrated by high-resolution AS-OCT.

Changes in corneal biomechanics in patients with keratoconus after penetrating keratoplasty.

PURPOSE: To examine the biomechanical properties of keratoconic eyes following penetrating keratoplasty and to compare results with the biomechanical characteristics of manifest keratoconus, forme fruste keratoconus and normal eyes as measured with the Reichert ocular response analyzer (ORA). METHODS: This retrospective analysis comprised a total of 169 eyes: 34 eyes with forme fruste keratoconus (group FF), 36 eyes with manifest keratoconus (Group KC), 36 eyes that have undergone penetrating keratoplasty (Group PK) and a control group of 63 normal eyes (Group N). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure, and Goldmann correlated intraocular pressure were measured by ORA. Central corneal thickness was calculated by the integrated handheld ultrasonic pachymeter of the ORA. The statistical analysis focused on CH and CRF changes among the 4 groups. RESULTS: When compared with normal eyes, mean CH and CRF values were found significantly lower in all groups (P < 0.05). Mean CH values were 8.19 ± 1.49 mm Hg in Group KC, 9.21 ± 1.38 mm Hg in Group FF, 10.16 ± 1.93 mm Hg in Group PK, and 11.43 ± 1.52 mm Hg in normal eyes (Group N). Although there was not a significant difference in mean CH values between Groups PK and FF (P = 0.072), the difference was significant between Groups KC as well as FF and Groups KC and PK (P < 0.05). Mean CRF values were found as 6.79 ± 1.81 mm Hg (Group KC), 8.21 ± 1.64 mm Hg (Group FF), 9.94 ± 2.34 mm Hg (Group PK), and 11.53 ± 1.83 mm Hg in Group N. The difference was statistically significant among all groups (P < 0.05). CONCLUSIONS: Penetrating keratoplasty has a beneficial effect on corneal biomechanics in keratoconic eyes. CH and CRF parameters approach the range of normal eyes after corneal transplantation.

Assessment of anterior chamber depth using Visante optical coherence tomography, slitlamp optical coherence tomography, IOL Master, Pentacam and Orbscan IIz.

AIMS: To assess and compare the anterior chamber depth (ACD) by different anterior segment imaging techniques. METHODS: Eighty healthy eyes of 40 patients were recruited, and 3 consecutive measurements of ACD were determined prospectively utilizing Visante optical coherence tomography (OCT), slitlamp (SL) OCT, IOL Master, Pentacam and Orbscan IIz. The statistical significance of interdevice differences between measurements was evaluated by one-way ANOVA and Bland-Altman analysis. The repeatability of 3 consecutive measurements was analyzed by repeated-measures ANOVA. RESULTS: The mean ACD was 2.98 ± 0.29, 2.85 ± 0.29, 3.33 ± 0.42, 2.93 ± 0.30 and 2.80 ± 0.29 mm with Visante OCT, SL-OCT, IOL Master, Pentacam and Orbscan IIz, respectively. All devices displayed a high intrasession repeatability (repeated-measures ANOVA, p > 0.05). ACD measurements obtained by the IOL Master were significantly greater compared to other devices. ACD values detected by Visante OCT and SL-OCT, Pentacam and Orbscan IIz were not clinically interchangeable, even though no statistically significant difference was detected. CONCLUSION: Although noncontact ACD measurements using all modalities were easy to handle and demonstrated good repeatability, the tested devices were not regarded as compatible. Hence, the clinician should take the different modalities into consideration during ACD assessment using various devices.

Descemet-stripping automated endothelial keratoplasty in eyes with toxic anterior segment syndrome after cataract surgery.

PURPOSE: To report the results of Descemet-stripping automated endothelial keratoplasty (DSAEK) in eyes with toxic anterior segment syndrome (TASS) after cataract surgery. SETTING: Department of Ophthalmology, Istanbul University Cerrahpasa Medical Faculty, Istanbul, Turkey. METHODS: In this prospective study of consecutive patients who had DSAEK for corneal failure due to TASS, the main outcome measures were corneal clarity, mean spherical equivalent (SE) refraction, preoperative and postoperative visual acuities, central corneal thickness, and endothelial cell count (ECC). RESULTS: The mean follow-up in the 10 eyes (10 patients) was 17.1 months +/- 2.4 (SD). There were no graft dislocations postoperatively, and no graft required repositioning. All grafts were clear at 12 months. Two eyes had initial graft rejection that resolved with treatment. All eyes had improved postoperative corrected distance visual acuity, with 7 eyes (70%) attaining 0.5 or better. The mean SE refraction in measurable cases (5 eyes) was 1.2 +/- 0.6 preoperatively and 0.9 +/- 1.0 postoperatively (P = .141). The decrease in mean pachymetry from preoperatively (691 +/- 15 microm) to 12 months postoperatively (614 +/- 23 microm) was statistically significant (P = .005). The mean ECC was 2740 +/- 236 cells/mm(2) preoperatively, 1690 +/- 209 cells/mm(2) at 6 months, and 1683 +/- 206 cells/mm(2) at 12 months. The decrease between preoperatively and 6 and 12 months (P = .05) and between 6 months and 12 months (P = .008) was statistically significant. CONCLUSION: Descemet-stripping automated endothelial keratoplasty was safe and effective in eyes with TASS-associated corneal edema, yielding encouraging surgical and visual outcomes.

Polymorphisms of the DNA repair genes XPD and XRCC1 and the risk of age-related macular degeneration.

PURPOSE: Oxidative stress seems to be an important factor in the development of age-related macular degeneration (AMD). The role of DNA repair mechanisms has also received attention recently in AMD pathogenesis. This case-control study was conducted to determine the frequency of polymorphisms in two DNA repair enzyme genes, xeroderma pigmentosum complementation group D (XPD), codons 312 and 751, and x-ray cross-complementing group 1 (XRCC1), codons 194 and 399, in patients with AMD and in disease-free control subjects. METHODS: Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to analyze XPD Asp312Asn and Lys751Gln and XRCC1 Arg194Trp and Arg399Gln in 120 patients with AMD (65 with dry type and 55 with wet type) and in age-matched 205 disease-free control subjects. RESULTS: Genotypic and allelic distributions of the polymorphisms were detected. For the XPD polymorphism, although the allele frequencies were not different between the patients and healthy control subjects, there was a significant difference between frequencies for the XPD751 Gln/Gln genotype in AMD patients (9%) and healthy control subjects (19%; P=0.02). The XPD751 Gln/Gln genotype seemed to have a protective effect against development of AMD (odds ratio, 0.41; 95% confidence interval, 0.19-0.88). Stratification by subtype of AMD revealed that the XPD751 Gln/Gln genotype was significantly lower only in the patients with dry type (P=0.02). These interactions remained nearly significant after Bonferroni correction (P<0.0125). Haplotype analysis for the two XPD polymorphisms revealed that the haplotype GC (312Asp-(751)Gln) was a protective haplotype against AMD. No statistically significant difference was found for the genotypic and allelic distributions of the polymorphisms in the XRCC1 gene between the patients and the control subjects. CONCLUSIONS: Polymorphism in XPD codon 751 may be associated with the development of AMD.

Assessment and comparison of anterior chamber dimensions using various imaging techniques.

BACKGROUND AND OBJECTIVE: To assess and compare the horizontal dimensions of the anterior chamber by different anterior segment imaging techniques. PATIENTS AND METHODS: Eighty eyes of 40 patients without any ocular disease or previous ocular surgery were recruited and three consecutive measurements of internal anterior chamber diameter and white-to-white distance (WTW) parameters were determined. RESULTS: Mean internal anterior chamber diameter was 11.80 +/- 0.39, 11.56 +/- 0.47, and 11.61 +/- 0.58 mm with Visante-OCT, SL-OCT, and Pentacam, respectively. Mean WTW distance was 11.87 +/- 0.35 and 11.65 +/- 0.32 mm by IOLMaster and OrbscanIIz, respectively. There was no significant difference between Visante-OCT and Pentacam, IOLMaster, and OrbscanIIz (P = .125, .918, and .314). However, detection of mean internal anterior chamber diameter was significantly greater by Visante-OCT than SL-OCT (P = .026). All devices displayed a high intrasession repeatability (repeated measured ANOVA, P > .05). CONCLUSION: Internal anterior chamber diameter measurements using Visante-OCT, SL-OCT, and Pentacam, and WTW measurements using IOLMaster and OrbscanIIz were easy to handle and demonstrated good repeatability. Although similar results of horizontal anterior chamber diameter were determined by Visante-OCT, Pentacam, IOLMaster, and OrbscanIIz, the inter-device differences should be considered during clinical practice.

Assessment of anterior chamber angle using Visante OCT, slit-lamp OCT, and Pentacam.

PURPOSE: To assess and compare the anterior chamber angle (ACA) by different anterior segment imaging techniques. METHODS: Forty healthy eyes of 40 normal subjects were recruited and 3 consecutive measurements of ACA were determined prospectively utilizing Visante optical coherence tomography (OCT), slit-lamp OCT (SL-OCT), and Pentacam. Statistical significance of interdevice differences between measurements was evaluated by Wilcoxon signed rank test and Bland-Altman analysis. The repeatability of 3 consecutive measurements was analyzed by repeated measured analysis of variance. RESULTS: Mean nasal and temporal ACA were detected as 31.2+/-8.7 and 32.1+/-8.5 degrees by Visante OCT; 41.6+/-5.9 and 41.8+/-5.2 degrees by Pentacam; and 42.9+/-10.0 and 43.3+/-10.1 degrees by SL-OCT. All devices displayed a high intrasession repeatability (Scheffe multiple comparison, p>0.05). ACA detected by Visante OCT were found significantly different from ACA calculated by Pentacam and SL-OCT (p<0.05). On the other hand, ACA data obtained by Pentacam and SL-OCT were found to be statistically similar (p>0.05). CONCLUSIONS: Although noncontact ACA measurements using all modalities were easy to handle and demonstrated good repeatability in healthy participants, the tested devices were not regarded as comparable. Hence, the clinician should take the different modalities into consideration during ACA assessment using various devices.

Correlation of retinal sensitivity and retinal thickness in central serous chorioretinopathy.

AIM: To evaluate the correlation of microperimetry (MP) and optical coherence tomography (OCT) in eyes having acute onset of central serous chorioretinopathy (CSCR). METHODS: After a detailed ophthalmological examination, all cases were evaluated by fundus fluorescein angiography, OCT and MP. Mean macular thickness was detected by OCT. Mean macular sensitivity (MS) and mean defect (MD) were determined by MP. The correlation between OCT and MP findings was analyzed by Spearman's correlation test. RESULTS: Fifteen eyes with CSCR of 15 patients with a mean age of 40.5 +/- 6.7 years were recruited. The mean visual acuity was 0.7 +/- 0.2, and the mean macular thickness was 348.9 +/- 75.8 mum. Mean MS and MD were 13.9 +/- 4.6 and -5.2 +/- 4.1 dB, respectively. The mean macular thickness was significantly correlated with both mean MS and MD (p = 0.011 and p = 0.017, respectively). A significant correlation was also found between mean macular thickness, MS and MD in the central 1 mm, superior 3 mm and nasal 3 mm of the macula (p < 0.05). CONCLUSIONS: Our results demonstrated a significant correlation between structural and functional changes in CSCR. MP provides quantitative measurements of central macular function in CSCR that may supplement OCT findings as well as the better understanding of visual functions during the acute stage of the disease.

Diurnal variation of corneal biomechanics and intraocular pressure in normal subjects.

PURPOSE: To assess and investigate the relationship between diurnal variations in intraocular pressure (IOP) and biomechanical properties of cornea. METHODS: Sixty-two healthy volunteers were recruited. Corneal compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal resistance factor (CRF), and corneal hysteresis (CH) parameters were recorded by the Ocular Response Analyzer (ORA). Central corneal thickness (CCT) was measured using an ultrasonic pachymeter. Three consecutive measurements of IOPcc, IOPg, CRF, CH, and CCT were recorded at 8:00 am, 11:00 am, 2:00 pm, and 5:00 pm. One-way analysis of variance and Pearson correlation tests were used for statistical analysis. Intra device repeatability was evaluated using Scheffe multiple comparison. RESULTS: IOPcc, IOPg, CRF, CH, and CCT measurements displayed a stable profile during daytime acquisitions and no statistically significant variation was noted (p>0.05). All measurements of IOPcc, IOPg, CRF, and CH recorded by ORA at 8:00 am, 11:00 am, 2:00 pm, and 5:00 pm were all found to be highly repeatable (p>0.05). There was a statistically significant and inverse correlation between IOPcc and CH (p=0.001), and a positive correlation was detected between IOPcc and CRF (p=0.001). CRF and CH were both found to be positively correlated to CCT (p=0.001). CONCLUSIONS: IOPcc readings and recordings of corneal biomechanics were constant throughout the day in healthy eyes. CRF and CH seem to exert different effects on IOPcc as diverse correlations were detected between CRF, CH, and IOPcc. Assessment of IOP and corneal biomechanics using ORA was found to be a highly repeatable.

Immediate evaluation of the flaps created by femtosecond laser using anterior segment optical coherence tomography.

BACKGROUND AND OBJECTIVE: To demonstrate the practical and functional evaluation of flaps created intraoperatively by femtosecond laser using anterior segment optical coherence tomography (AS-OCT). PATIENTS AND METHODS: The study prospectively examined 11 eyes of 6 patients who underwent uneventful LASIK surgery with the aid of the IntraLase femtosecond laser (IntraLase Corp., Irvine, CA). During the waiting period between femtosecond laser and excimer laser, all eyes were evaluated by AS-OCT to image each flap immediately before flap lifting and laser ablation. Flap thickness and residual stromal bed thickness were calculated automatically using the software's flap tool. RESULTS: A uniform flap was created by femtosecond laser not only in the central cornea, but also in all quadrants. CONCLUSION: The qualitative and quantitative evaluation of the corneal flap created by a femtosecond laser using AS-OCT before lifting the flap confirms that the femtosecond laser is a practical intraoperative approach that offers a safer surgery.