Ocular perfusion pressure and choroidal thickness in eyes with polypoidal choroidal vasculopathy,wet-age-related macular degeneration,and normals

Purpose

To measure the choroidal thickness and ocular perfusion pressure in eyes with polypoidal choroidal vasculopathy (PCV), wet-age-related macular degeneration (AMD), and age-matched normal subjects, and look for a possible association between the two.

Methods

This was a prospective study including 22 eyes with PCV, 33 eyes with wet-AMD, and 35 age-matched normal eyes. Choroidal thickness was measured using enhanced depth imaging (EDI) with spectral-domain optical coherence tomography (SD OCT). Mean ocular perfusion pressure (MOPP) was calculated using the mathematical formula 2/3[DBP+1/3{SBP × DBP}]−IOP (DBP—diastolic blood pressure, SBP—systolic blood pressure, IOP—intraocular pressure). Analyses were carried out using SPSS 14 software and comparisons of mean made using‘t'' tests.

Results

Eyes with PCV showed increased (285.9 μm; subfoveal) choroidal thickness, whereas eyes with wet-AMD (119.4 μm; subfoveal) showed reduced choroidal thickness in comparison with normal eyes (186.77 μm; subfoveal). MOPP in the PCV group was 57.85 mm Hg (P value 0.00), in the wet-AMD group was 52.1 mm Hg (P-value 0.12), and in the normal group was 49.79 mm Hg.

Conclusion

It is postulated that higher MOPP in eyes with PCV could have an etiologic implication in disease manifestation and progression. Larger studies with longer follow-up may help validate these findings.     

Evaluation of choroidal thickness using enhanced depth imaging by spectral-domain optical coherence tomography in patients with pseudoexfoliation syndrome

Purpose

To investigate the choroidal thickness using optical coherence tomography in the eyes of patients with unilateral and bilateral pseudoexfoliation syndrome and to compare them with healthy controls.

Methods

We studied four groups: (1) affected eyes from 30 patients with unilateral PEX syndrome affecting the right eye of 17 patients and the left eye of 13 patients; (2) clinically unaffected eyes of 30 patients with unilateral PEX syndrome; (3) the eyes of 30 patients with bilateral PEX syndrome; and (4) the eyes of 30 normal healthy subjects. Choroidal thickness was evaluated using high-speed, high-resolution enhanced depth imaging by spectral-domain optical coherence tomography. Optical coherence tomography features were compared in all groups using the statistical package SPSS v 15.0.

Results

The mean subfoveal choroidal thicknesses were 237.35±58.01 μm in group 1; 330.75±47.84 μm in group 2; 206.3±86.75 μm in group 3; and 311.8±51.42 μm in group 4. Significant differences in the mean subfoveal choroidal thickness were found between groups 1 and 2 (P<0.001), groups 1 and 4 (P=0.004), groups 2 and 3 (P<0.001), and groups 3 and 4 (P<0.001).

Conclusion

In this study, it was observed that clinically affected eyes of patients with PEX syndrome have significantly thinner choroids compared with the clinically unaffected eyes of patients with unilateral PEX syndrome and eyes of healthy controls.     

Structural changes of the choroid in sarcoid- and tuberculosis-related granulomatous uveitis

Aim

The aim of this study is to characterise the choroidal features of patients diagnosed with sarcoid- and tuberculosis (TB)-associated granulomatous uveitis using spectral domain optical coherence tomography (OCT).

Methods

Twenty-seven patients (27 eyes) diagnosed with sarcoid- (13 eyes) and TB (14 eyes)-related uveitis were included in this retrospective, cross-sectional study. Over a six-month period, patients diagnosed with sarcoid and TB granulomatous uveitis were scanned using enhanced depth imaging OCT. Clinical and demographical characteristics were recorded, including the method of diagnosis, disease activity, site of inflammation (anterior or posterior), treatments, and visual acuity (VA). Manual segmentation of the choroidal layers was performed using custom image analysis software.

Results

The main outcome measure was OCT-derived thickness measurements of the choroid and choroidal sublayers (Haller''s large vessel and Sattler''s medium vessel layers) at the macula region. The ratio of Haller''s large vessel to Sattler''s medium vessel layer was significantly different at the total macula circle in eyes diagnosed with TB uveitis (1.47 (=140.71/95.72 μm)) compared with sarcoid uveitis (1.07 (=137.70/128.69 μm)) (P=0.001). A thinner choroid was observed in eyes with a VA ≥0.3 LogMAR (Snellen 6/12; 198.1 μm (interquartile range (IQR)=147.0–253.4 μm) compared with those with VA <0.3 LogMAR (292.4 μm (IQR=240.1–347.6 μm)) at the total macula circle (P=0.004). At the foveal central subfield, the median choroidal thickness was 336.8 μm (IQR=272.3–375.4 μm) in active compared with 239.3 μm (IQR=195.3–330.9 μm) in quiescent disease (P=0.04).

Conclusion

A disproportionately enlarged Sattler''s layer may indicate a diagnosis of sarcoid-related uveitis, and choroidal thickening may be a feature of active granulomatous uveitis.     

Variability of subfoveal choroidal thickness measurements in patients with age-related macular degeneration and central serous chorioretinopathy

Purpose

To evaluate the variability in subfoveal choroidal thickness measurements in patients with age-related macular degeneration (AMD) and central serous chorioretinopathy using enhanced depth imaging optical coherence tomography (EDI-OCT).

Methods

One hundred and sixty eyes of 160 patients who were diagnosed with early AMD (N=40), exudative AMD (N=40), polypoidal choroidal vasculopathy (PCV, N=40), or central serous chorioretinopathy (CSC, N=40) were included in this retrospective observational study. In addition, we included 40 normal eyes of 40 subjects. Subfoveal choroidal thickness was measured manually by two masked observers based on EDI-OCT images. The correlation of choroidal thickness with the absolute value of the difference in the choroidal thickness measurement was estimated for all 200 eyes. Intraobserver and interobserver coefficients of repeatability (CRs) were calculated.

Results

There was a significant positive correlation between subfoveal choroidal thickness and both intraobserver (P<0.001) and interobserver (P<0.001) difference in choroidal thickness measurements. The mean intraobserver CRs in nonexudative AMD, exudative AMD, PCV, CSC, and normal eyes were ∼15–21, 23–29, 24–35, 32–38, and 19–25 μm, respectively. The mean interobserver CRs were ∼24–28, 30–36, 39–45, 46–57, and 26–35 μm, respectively.

Conclusions

Relatively great measurement variability should be considered when investigating eyes with pathologic conditions related to a thick choroid, including PCV or CSC.     

Chorio-retinal thickness measurements in patients with acromegaly

Purpose

To compare choroidal, foveal, and peripapillary retinal thickness between patients with acromegaly and healthy adults.

Methods

This prospective, cross-sectional, and comparative study included 30 patients with acromegaly (study group) and 30 healthy subjects (control group). The subfoveal choroidal thickness (SFCT), foveal thickness, and peripapillary retinal nerve fibre layer thickness were measured with spectral domain optical coherence tomography.

Results

The mean SFCT in the study group and in the control eyes was 374.4±98.1 and 308.6±77.3 μm, respectively (P<0.001). The mean thinnest foveal thickness value was 233.2±22.4 μm in the acromegaly group and 222.8±13.9 μm in the control group (P=0.003). The mean peripapillary retinal nerve fibre layer thickness did not differ significantly between the groups (P=0.34).

Conclusion

The SFCT and foveal thickness were significantly higher in patients with acromegaly, whereas peripapillary retinal nerve fibre layer thickness was similar between the groups.     

Two-year results of intravitreal ranibizumab for polypoidal choroidal vasculopathy with recurrent or residual exudation

Aim

To clarify the 2-year efficacy of ranibizumab for patients with polypoidal choroidal vasculopathy (PCV) with recurrent or residual exudation from branching vascular networks after previous photodynamic therapy (PDT).

Methods

We retrospectively reviewed 26 eyes of 26 Japanese patients (22 men, 4 women) in this pilot study. All eyes had PCV with complete regression of polypoidal lesions resulting from PDT detected by indocyanine green angiography (ICGA), but recurrent or residual leakage from branching vascular networks on fluorescein angiography and evidence of persistent fluid on optical coherence tomography (OCT). Three consecutive intravitreal injections of ranibizumab (0.5 mg/0.05 ml) were administered to all eyes.

Results

The mean logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) improved significantly from 0.55 at baseline to 0.35 at 12 months (P<0.0001) and 0.43 at 24 months (P=0.0012). The mean increases in the BCVA 12 and 24 months after baseline were 1.95 and 1.23 lines, respectively. The mean central retinal thickness significantly decreased from 295 μm at baseline to 189 μm at 12 months (P<0.0038) and 163 μm at 24 months (P<0.001). The mean numbers of intravitreal ranibizumab (IVR) injections at months 12 and 24, including the initial treatments, were 5.8 and 8.8, respectively. Five (19.2%) eyes had recurrent polypoidal lesions on ICGA at a mean of 15.7 months after baseline. At month 24, OCT showed no exudation in 17 (65.4%) of the 26 eyes. No adverse events developed.

Conclusions

IVR injections maintained or improved the VA and retinal thickness at 24 months in eyes with PCV with recurrent or residual exudation from branching vascular networks after previous PDT.     

Evaluation of ocular pulse amplitude and choroidal thickness in diabetic macular edema

Purpose

The aim of this study is to evaluate the ocular pulse amplitude (OPA) and choroidal thickness (CT) measurements in patients with diabetic macular edema (DME) and healthy subjects.

Methods

A total of 34 patients (12 male and 22 female) who had type 2 diabetes mellitus with DME and 34 sex-matched healthy subjects (13 male and 21 female) were included in this prospective study. The intraocular pressure (IOP) and OPA were measured with Dynamic contour tonometer (Pascal DCT, Switzerland). The subfoveal CT was measured using the Cirrus HD-OCT (Carl Zeiss Meditec). The CT at 1500 μm and 3000 μm nasal and temporal to the central fovea was also measured.

Results

The mean IOP values were 18.4±3.5 and 17.1±2.1 mm Hg in DME patients and healthy controls, respectively (P= 0.091). The mean OPA values in patients with DME (2.58±0.96) and controls (3.52±1.03) were statistically different (P<0.001). The mean subfoveal CT value was 273.5±30.2 μm in the eyes with DME and 321.4±36.5 μm in the control group (P< 0.001). In both groups, linear regression analysis showed no significant association between OPA and CT measurements. The IOP showed a significantly positive correlation with OPA in both DME (P=0.002, r=0.526) and controls (P=0.004, r=0.483).

Conclusions

The current study suggests that both pulsatile choroidal blood flow and CT are decreased in patients with DME.     

Evaluation of choroidal thickness using spectral-domain optical coherence tomography in migraine patients during acute migraine attacks: a comparative study

Purpose

The purpose of this study was to assess choroidal thickness in migraine patients during acute migraine attacks and compare them with healthy controls, using spectral domain optical coherence tomography (OCT).

Patients and methods

In this prospective case–control study, choroidal thicknesses of 46 migraine patients during acute migraine attacks and 46 age- and sex-matched healthy subjects were measured using a high-speed, high-resolution frequency domain-OCT device. All patients underwent a complete ophthalmic examination before the measurements. OCT measurements were taken at the same time of day (0900 hours), in order to minimize the effects of diurnal variation.

Results

There was a statistically significant difference in mean choroidal thickness between the migraine patients during acute migraine attacks (356.3±21.46 μm) and the controls (302.3±18.34 μm; P=0.000). There were significant differences at all measurement points (P<0.001 for all).

Conclusion

The increased choroidal thickness of the migraine patients during acute migraine attacks might be related to the vascular pathology of the disease. Further studies are needed to evaluate the etiopathologic relationship between choroidal thickness and acute migraine attack.     

Choroidal thickness in both eyes of patients with unilaterally active central serous chorioretinopathy

Objective

To assess the change in the choroidal thickness of the unaffected eyes in patients with unilateral central serous chorioretinopathy (CSC).

Methods

Thirty eyes with unilateral idiopathic CSC and 30 age-matched normal eyes were included in this study. Choroidal thickness was evaluated from images obtained by enhanced depth image optical coherence tomography. The choroidal thicknesses of the affected eyes, unaffected eyes, and normal eyes were analyzed. Choroidal vascular dilation and hyperpermeability on indocyanine green angiography (ICGA) were analyzed and correlated with the changes in choroidal thickness.

Results

The mean choroidal thicknesses of the affected eyes, unaffected fellow eyes, and normal individuals were 445.58±100.25, 378.35±117.44, and 266.80±55.45 μm, respectively. Compared with normal eyes, subfoveal choroidal thickness was increased significantly in the eyes with active CSC and in the unaffected fellow eyes (P<0.001 in both groups). The choroidal thickness was significantly greater in the eyes with active CSC than in the unaffected fellow eyes (P=0.003). ICGA revealed choroidal vascular hyperpermeability in 28 (93.3%) eyes with CSC and in 23 (73.3%) unaffected fellow eyes. Choroidal vascular dilation was detected in 21 (70.0%) eyes with CSC and in 18 (60.0%) unaffected fellow eyes.

Conclusion

Increased choroidal thickness in patients with unilateral CSC was noted not only in the affected eyes, but also in the unaffected fellow eyes. The results of this study suggest that CSC might be an essentially bilateral disorder.     

Correlation of subretinal fluid volume with choroidal thickness and macular volume in acute central serous chorioretinopathy

Purpose

To evaluate the correlation of subretinal fluid volume with choroidal thickness and macular volume in acute central serous chorioretinopathy (CSC).

Methods

Twenty patients with acute unilateral treatment-naive idiopathic CSC and 20 age-matched normal eyes were included in this prospective cross-sectional study. Subretinal fluid volume (SRFV) of study eyes was estimated using a built-in segmentation-modifying tool of Spectralis spectral-domain optic coherence tomography (SD-OCT). Subfoveal choroidal thickness (SCT) (measured with enhanced depth imaging-OCT) and macular volume (MV) were also determined. The correlation of SRFV with SCT and MV was analyzed statistically.

Results

There was no significant correlation of SRFV with SCT and MV in the study eyes (r=0.062, P=0.796 and r= −0.061, P=0.798, respectively). The mean SCT of the study eyes, the fellow eyes and the control eyes were 461.4±101.4, 375.3±103.7, 287.6±62.5 μm, respectively (P<0.001). The mean modified MV (determined excluding SRF volume) of the study eyes, the macular volume of the fellow and the control eyes was 8.57±0.59 mm³, 8.75±0.4 mm³ and 8.73±0.38 mm³, respectively (P>0.05).

Conclusions

The current study shows that subretinal fluid volume does not correlate with subfoveal choroidal thickness. This novel finding suggests that formation of subretinal fluid is not solely associated with choroidal vasculature in acute CSC.     

Scleral thickness in highly myopic eyes measured by enhanced depth imaging optical coherence tomography

Purpose

The purpose of this study was to determine the subfoveal scleral thickness in highly myopic eyes by enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT) and to identify the ocular parameters significantly associated with the scleral thickness.

Methods

The subfoveal scleral thickness of myopic eyes (≥−8 diopters (D) or axial length ≥26.5 mm) was examined by EDI-OCT. The correlations between the thickness and the best-corrected visual acuity (BCVA), refractive error, axial length (AL), the subfoveal retinal thickness, choroidal thickness, and posterior staphyloma height 2 mm from the fovea were investigated.

Results

A total of 75 eyes of 54 patients (21 men, 33 women; mean age, 62.3±11.3 years; mean AL, 30.2±1.68 mm) were studied. Eighteen eyes had no pathological retinochoroidal lesions, and 57 eyes had retinochoroidal lesion, that is, myopic schisis, choroidal neovascularization, and other retinochoroidal pathologies. The mean subfoveal scleral thickness was 284.0±70.4 μm, and the thickness was significantly correlated negatively with the absolute value of the nasal and overall average posterior staphyloma height (P<0.05 and P<0.01, respectively). The subfoveal scleral thickness was also significantly correlated negatively with the relative value of the superior, nasal, and overall average posterior staphyloma height (P<0.05, P<0.01, and P<0.001, respectively). Stepwise analyses showed that the factor most significantly associated with the scleral thickness was the average relative posterior staphyloma height (F=16.0, P<0.001). The scleral thickness was not significantly different between eyes with and without myopic retinochoroidal pathologies (P>0.05).

Conclusion

Posterior staphyloma formation was a key factor associated with a posterior scleral thinning in highly myopic eyes.     

Observational study of subclinical diabetic macular edema

Purpose

To determine the rate of progression of eyes with subclinical diabetic macular edema (DME) to clinically apparent DME or DME necessitating treatment during a 2-year period.

Methods

In all, 43 eyes from 39 study participants with subclinical DME, defined as absence of foveal center edema as determined with slit lamp biomicroscopy but a center point thickness (CPT) between 225 and 299 μm on time domain (Stratus, Carl Zeiss Meditec) optical coherence tomography (OCT) scan, were enrolled from 891 eyes of 582 subjects screened. Eyes were evaluated annually for up to 2 years for the primary outcome, which was an increase in OCT CPT of at least 50 μm from baseline and a CPT of at least 300 μm, or treatment for DME (performed at the discretion of the investigator).

Results

The cumulative probability of meeting an increase in OCT CPT of at least 50 μm from baseline and a CPT of at least 300 μm, or treatment for DME was 27% (95% confidence interval (CI): 14%, 38%) by 1 year and 38% (95% CI: 23%, 50%) by 2 years.

Conclusions

Although subclinical DME may be uncommon, this study suggests that between approximately one-quarter and one-half of eyes with subclinical DME will progress to more definite thickening or be judged to need treatment for DME within 2 years after its identification.     

Drusen prevalence and pigmentary changes in Caucasians aged 18–54 years

Aims and Purpose

The aim of this study was to describe the prevalence and characteristics of drusen and pigmentary changes in a middle-aged population.

Methods

Retinal images from 500 individuals aged 18–54 years were included. The source of participants was two UK optometry practices. Retinal images were graded using the Wisconsin Age-Related Maculopathy Grading System. However, owing to the relatively young age of the population studied, a new category of drusen of smaller size (<31.5 μm) was introduced.

Results

Drusen were identified within the central macular grid in 91.48% of all gradable eyes and in 444 subjects. Drusen sized <31.5 μm were present in 89.7% of eyes, drusen sized >31.5 μm and <63 μm were present in 45.9% of all eyes and drusen >63 μm and <125 μm were present in only 1.7% of eyes. No eye had drusen larger or equal to 125 μm. Very few eyes (1.2%) showed pigmentary changes within the grid. Drusen load increased with increasing age, P <0.001.

Conclusions

The frequency of drusen in a younger Caucasian population aged 18–54 years is high, with 91.48% of all gradable eyes having drusen. The most frequent drusen subtype was hard distinct drusen <31.5 μm. No druse greater or equal in size to 125 μm was seen. Pigmentary changes are rare.     

Retention of good visual acuity in eyes with neovascular age-related macular degeneration and chronic refractory subfoveal subretinal fluid

Purpose

To describe the clinical characteristics of a subset of eyes with neovascular age-related macular degeneration (NVAMD) receiving intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy which retain good visual acuity despite chronic, persistent subfoveal subretinal fluid (SRF).

Design

Retrospective, observational case series.

Methods

Study eyes were identified from a consecutive series of 186 patients treated with anti-VEGF therapy seen for regular follow-up over a 3-month period. The clinical histories of 10 eyes of 9 patients with NVAMD, chronic subfoveal SRF despite continuous anti-VEGF therapy, and good long-term visual acuity of 20/40 or greater were reviewed. Demographic factors, baseline and final visual acuity, neovascular lesion type, duration of persistent fluid, baseline and final subfoveal choroidal thickness, presence of geographic atrophy, and number of anti-VEGF injections were analyzed.

Results

The mean age of patients was 78 years (range 55–91). The mean duration of persistent fluid was 5.2 years (range 1.3–11.0). Long-term visual acuities remained stable at 20/40 or better in all eyes. All eyes had type 1 (sub-retinal pigment epithelial) neovascularization. Average baseline subfoveal choroidal thickness was 285.3 μm and the average follow-up subfoveal choroidal thickness was 239.7 μm. No eyes had the presence of geographic atrophy. The mean number of injections was 36.5 (range 17–66).

Conclusion

Some eyes with type 1 neovascularization associated with chronic persistent subfoveal subretinal fluid despite continuous intravitreal anti-VEGF therapy may maintain good long-term visual outcomes. We hypothesize that type 1 neovascularization and greater subfoveal choroidal thickness may exert a protective effect on photoreceptor integrity. Further studies are necessary to assess long-term visual prognosis and predictive factors in patients with type 1 neovascularization leading to persistent subretinal fluid that is recalcitrant to anti-VEGF treatment.     

Change in subfoveal choroidal thickness in central serous chorioretinopathy following spontaneous resolution and low-fluence photodynamic therapy

Purpose

To assess the change in subfoveal choroidal thickness (SFCT) in central serous chorioretinopathy (CSC) following spontaneous resolution and low-fluence photodynamic therapy (PDT) using the enhanced depth imaging optical coherence tomography (EDI-OCT).

Methods

A total of 36 consecutive eyes of 36 patients were included in this retrospective study: 16 eyes with spontaneously resolved CSC and 20 eyes with PDT-treated CSC. Best-corrected visual acuity and SFCT were evaluated at each visit until complete absorption of the subretinal fluid. SFCT of 32 normal subjects were also measured, as the control group. Wilcoxon''s singed-rank test was used to evaluate the effects of spontaneous resolution and PDT. To compare the SFCT of the eyes with resolved CSC with that of the normal eyes, Mann–Whitney U-test with Bonferroni correction was also employed.

Results

SFCT of patients was 459.16±77.50 μm at the baseline, and decreased to 419.31±54.49μm after a spontaneous resolution (P=0.015). However, SFCT was not normalized in comparison with that of the normal subjects (P<0.001). SFCT in PDT group was also reduced from 416.43±74.01 to 349.50±88.99 μm (P<0.001), with no significant difference with the normal value (P=0.087).

Conclusions

SFCT in patients with CSC decreased both after spontaneous resolution and low-fluence PDT. However, only in the PDT group, after disappearance of subretinal fluid, did it decrease to that of normal subjects.     

Smoking and choroidal thickness in patients over 65 with early-atrophic age-related macular degeneration and normals

Objective

To compare macular choroidal thickness between cigarette smokers, those with a history of smoking, and nonsmokers in patients over 65 years of age with early-atrophic age-related macular degeneration (AMD) and normals.

Methods

Prospective, consecutive, observational case series. Enhanced depth imaging spectral domain optical coherence tomography 12-line radial scans were performed and choroidal thickness manually quantified at 84 points in the central 3 mm of the macula. Data of normals, soft drusen alone, and soft drusen with additional features of early AMD were compared. A multivariate analysis of variance (MANOVA) model, controlling for age, was constructed to evaluate the effect of smoking history and AMD features on choroidal thickness.

Results

A history of smoking was significantly associated with a thinner choroid across all patients via logistic regression (P=0.004; O.R.=12.4). Mean macular choroidal thickness was thinner for smokers (148±63 μm) than for nonsmokers (181±65 μm) among all diagnosis categories (P=0.003). Subgroup analysis of patients with AMD features revealed a similar decreased choroidal thickness in smokers (121±41 μm) compared with nonsmokers (146±46 μm, P=0.006). Bivariate analysis revealed an association between increased pack-years of smoking and a thin choroid across all patients (P<0.001) and among patients with features of early AMD (P<0.001). Both the presence of features of macular degeneration (P<0.001) and a history of smoking (P=0.024) were associated with decreased choroidal thickness in a MANOVA model.

Conclusion

Chronic cigarette smoke exposure may be associated with decreased choroidal thickness. There may be an anatomic sequelae to chronic tobacco smoke exposure that underlies previously reported AMD risk.     

Astigmatism and biometric optic components of diode laser-treated threshold retinopathy of prematurity at 9 years of age

Purpose

To assess the prevalence of astigmatism and its relationship with biometric optic components in preterm school children with diode laser-treated threshold retinopathy of prematurity (ROP).

Methods

A prospective, cross-sectional study in which cycloplegic keratometry, refraction, and ultrasound biometric measurement of optic components were performed on 24 consecutive preterm children with diode laser-treated threshold ROP at the age of 9 years. The study results were compared with data on 1021 age-matched full-term control children from a national survey.

Results

The laser-treated eyes had a mean astigmatism of 3.47 D, with a mean spherical equivalent of −4.49 D. Of the 46 eyes studied, 98% of eyes showed astigmatism ≥0.5 D and 50% had high astigmatism (>3.0 D). Most astigmatic eyes (97.7%) showed with-the-rule astigmatism, with the mean plus cylinder axis at 89.30^o. Further correlation analysis showed the astigmatism in refraction was highly correlated with the corneal astigmatism (r=0.921, P<0.001) and the vertical corneal curvature (r=0.405, P=0.005). There was significantly steeper vertical corneal curvature (P=0.003) and flatter horizontal corneal curvature (P=0.031) in eyes with laser-treated ROP when compared with age-matched full-term controls. The eyes with laser-treated ROP also show significantly thicker lens (3.93 mm) and shallower anterior chamber depth (ACD; 2.92 mm) than full-term controls (P<0.001).

Conclusions

There is significantly higher prevalence and greater magnitude of astigmatism in eyes with laser-treated threshold ROP compared with full-term controls. The steeper vertical corneal curvature component contributes to the increased astigmatism in eyes with laser-treated ROP.     

Focal choroidal excavation in patients with central serous chorioretinopathy

Purpose

To evaluate the prevalence and clinical features of focal choroidal excavation (FCE) in patients presenting with central serous chorioretinopathy (CSC).

Methods

This is a retrospective consecutive case series of consecutive patients with CSC who were referred for spectral domain optical coherence tomography (SD-OCT) between January 2010 and December 2011. Medical records were reviewed and clinical features including presence of FCE in SD-OCT, fluorescence angiography (FA), and indocyanine green angiography (ICGA) were studied.

Results

Among the 116 CSC patients assessed, FCE was found in 11 eyes of 7 (6.0%) patients. FCE was associated with subretinal fluid in six eyes of six patients and serous pigment epithelial detachment in three eyes of two patients. The mean central subfield retinal thickness of CSC eyes with FCE was 283.7 μm, compared with 377.5 μm for CSC eyes without FCE (Mann–Whitney U-test, P=0.020). Five FCE eyes of five patients had focal leakage on FA. Choroidal hyperpermeability on ICGA was found in seven CSC eyes with FCE, with four eyes showing hypofluorescent spot corresponding to the FCE. After a mean follow-up of 16 months, visual acuity of all 11 eyes with FCE remained stable or improved at the last follow-up.

Conclusion

FCE is not an uncommon feature in patients with CSC and might be associated with choroidal hemodynamic disturbances.     

Effect of OCT volume scan density on thickness measurements in diabetic macular edema

Purpose

To evaluate the impact of reducing B-scan frame-sampling density on retinal thickness measurements using spectral domain optical coherence tomography (SD-OCT) in eyes with diabetic macular edema (DME).

Methods

We retrospectively collected OCT data for 64 eyes of 43 patients undergoing imaging for DME using the Cirrus HD-OCT 512 × 128 macular cube protocol. For each case, raw OCT data were imported into the 3D-OCTOR software, and retinal thickness maps were generated using all 128 B-scans and for lower densities of B-scans ranging from every other scan to only four scans (every 30-s B-scan). Maps were generated before and after manual correction of retinal boundary segmentation errors. The foveal central subfield (FCS) and total macular volume (TMV) values were used to compare thickness maps of varying densities.

Results

The mean difference in FCS retinal thickness and TMV increased as the B-scan density was reduced, particularly when the density was reduced to fewer than 16 B-scans over 6 mm. At a density of 16 B-scans, the mean absolute difference in FCS thickness was 2.43 μm (0.79%), with a maximum of 10.1 μm (4.09%). At this density, the mean difference in TMV was 0.012 mm³ (0.13%), with a maximum difference of 0.04 mm³ (0.47%). Manual correction of OCT segmentation errors resulted in a difference in FCS thickness of ≥10 μm in only 12.5% of cases, with a maximum difference of 115.7 μm.

Conclusion

A minimum of 16 equally spaced B-scans appear necessary to generate retinal thickness measurements similar to those produced using all 128 B-scans in eyes with DME. Manual correction of segmentation errors appeared to have a clinically meaningful effect in a small minority of cases. These results may have implications for the design of SD-OCT imaging and grading protocols in clinical trials of DME, particularly when using multiple SD-OCT instruments that acquire varying numbers of B-scans.     

Comparison of retinal thickness values and segmentation performance of different OCT devices in acute branch retinal vein occlusion

Purpose

To compare retinal thickness (RT) measurement and segmentation performance of time domain (TD, Stratus) and spectral domain (SD) optical coherence tomography (OCT) devices (Cirrus, Spectralis) for imaging macular oedema (ME) secondary to branch retinal vein occlusion (BRVO).

Methods

In this study, 20 eyes of 20 consecutive patients with acute BRVO were included. A total of 18 unaffected fellow eyes served as control group. RT measurement was analysed in the five inner fields of the early-treatment diabetic retinopathy grid, and proportional segmentation errors were evaluated.

Results

Central millimetre thickness (CMT) showed a mean difference of −64, −74, and −18 μm (P<0.001) in the control group and −31 μm (P=0.107), −92 μm (P<0.001), and −105 μm (P=0.016) in the BRVO group, between Stratus and Cirrus, between Stratus and Spectralis, and between Cirrus and Spectralis, respectively. Mean RT showed the highest variability between different devices in the area most intensively affected by BRVO-related ME. In eyes with BRVO, 14.6% of Spectralis, 20% of Stratus, and 36.6% of Cirrus scans demonstrated moderate and severe segmentation errors.

Conclusion

RT measurement in eyes with BRVO, by TD and SD OCT, is compromised by a significant rate of segmentation errors. Deviations are most pronounced in the areas most severely affected by ME.