CHANGES OF OUTER RETINAL THICKNESS WITH INCREASING AGE IN NORMAL EYES AND IN NORMAL FELLOW EYES OF PATIENTS WITH UNILATERAL AGE-RELATED MACULAR DEGENERATION

Measurement of Iris Thickness at Different Regions in Healthy Chinese Adults

Purpose

To study the variation of iris thicknesses in different regions and explore the possible correlations with age and gender.

Methods

Healthy Chinese adults were recruited; the anterior segment of their eyes was imaged by swept-source optical coherence tomography (SS-OCT). The horizontal scan of the right eye was selected, and the thicknesses of both the nasal and temporal irises were measured at 199 evenly spaced points.

Results

A total of 233 subjects with an average age of 36.79 ± 10.04 years (range 19 to 62) were included in the final analysis. The mean iris thicknesses of the temporal and nasal sides were 364.79 ± 47.58 μm and 372.44 ± 43.75 μm, respectively. The mean nasal iris thickness was positively correlated with age (β = 0.9 μm/year; P = 0.002), but the temporal one was not (β = 0.077 μm/year; P = 0.806). At 139 points of the nasal iris and 146 points of the temporal iris, the iris thickness was significantly correlated with age (P < 0.05). The thicknesses of the peripheral and pupillary parts were positively correlated with age, while the middle part was negatively correlated with age. No significant difference was observed in the mean iris thickness between genders (temporal: t = 1.597, P = 0.112; nasal: t = 1.870, P = 0.063), but females had a thicker iris than males at 50 points in the temporal side and 49 points in the nasal side (P < 0.05); no point in males was observed to have thicker iris compared to females.

Conclusion

Using SS-OCT and the novel method, thicknesses of the iris at different regions were measured. The thicknesses of the peripheral and pupillary irises increase with age, while the thicknesses of the middle part decrease.

Retinal and Choroidal Thickness in relation to C-Reactive Protein on Swept-Source Optical Coherence Tomography

Purpose

To evaluate the relationships between C-reactive protein (CRP) and retinal and choroidal thickness by swept-source optical coherence tomography (SS-OCT).

Methods

The participants included in the prospective cross-sectional study underwent a comprehensive ophthalmic examination. Based on the CRP values, the subjects were divided into the CRP (+) group (CRP ≥ 8.2 mg/L) and the CRP (−) group (CRP < 8.2 mg/L). The retinal and choroidal thickness was compared between the two groups.

Results

This study enrolled 43 right eyes of 43 subjects from the CRP (+) group and 86 right eyes of 86 gender- and age-match subjects from the CRP (−) group. The choroidal thickness in the CRP (+) group was thinner than that in the CRP (−) group except for the outer nasal sector of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. However, the retinal thickness only in the inner temporal sector showed a significant difference. According to Pearson's correlation analysis, the CRP was significantly negatively correlated with the choroidal thickness in all sectors and the retinal thickness only in the inner temporal and outer nasal sectors of the ETDRS grid.

Conclusion

CRP levels are associated with retinal and choroidal thickness. The data related to the retinal and choroidal thickness changes may help understand the pathogenesis of specific ocular abnormalities in patients with systemic inflammation.

Modelling normal age-related changes in individual retinal layers using location-specific OCT analysis

Current descriptions of retinal thickness across normal age cohorts are mostly limited to global analyses, thus overlooking spatial variation across the retina and limiting spatial analyses of retinal and optic nerve disease. This retrospective cross-sectional study uses location-specific cluster analysis of 8 × 8 macular average grid-wise thicknesses to quantify topographical patterns and rates of normal, age-related changes in all individual retinal layers of 253 eyes of 253 participants across various age cohorts (n = 23-69 eyes per decade). Most retinal layers had concentric spatial cluster patterns except the retinal nerve fibre layer (RNFL) which displayed a nasal, asymmetric radial pattern. Age-related thickness decline mostly occurred after the late 4th decade, described by quadratic regression models. The ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), and outer nuclear layer + Henle's fibre layer (ONL_+HFL) were significantly associated with age (p < 0.0001 to < 0.05), demonstrating similar rates of thickness decline (mean pooled slope =  - 0.07 µm/year), while the IS/OS had lesser mean pooled thickness slopes for all clusters (- 0.04 µm/year). The RNFL, OPL, and RPE exhibited no significant age-related thickness change, and the RNFL were significantly associated with sex. Analysis using spatial clusters compared to the ETDRS sectors revealed more extensive spatial definition and less variability in the former method. These spatially defined, clustered normative data and age-correction functions provide an accessible method of retinal thickness analysis with more spatial detail and less variability than the ETDRS sectors, potentially aiding the diagnosis and monitoring of retinal and optic nerve disease.

Macular retinal thickness differs markedly in age-related macular degeneration driven by risk polymorphisms on chromosomes 1 and 10

The two most common genetic contributors to age-related macular degeneration (AMD), a leading cause of irreversible vision loss worldwide, are variants associated with CFH-CFHR5 on chromosome 1 (Chr1) and ARMS2/HTRA1 on chromosome 10 (Chr10). We sought to determine if risk and protective variants associated with these two loci drive differences in macular retinal thickness prior and subsequent to the onset of clinically observable signs of AMD. We considered 299 individuals (547 eyes) homozygous for risk variants or haplotypes on Chr1 or Chr10 exclusively (Chr1-risk and Chr10-risk, respectively) or homozygous for a neutral haplotype (Chr1-neu), for the protective I62 tagged haplotype (Chr1-prot-I62) or for the protection conferring CFHR1/3 deletion haplotype (Chr1-prot-del) on Chr1 without any risk alleles on Chr10. Among eyes with no clinically observable signs of AMD, the deletion of CFHR1/3, which is strongly protective against this disease, is associated with significantly thicker retinas in the perifovea. When controlling for age, Chr10-risk eyes with early or intermediate AMD have thinner retinas as compared to eyes from the Chr1-risk group with similar disease severity. Our analysis indicates that this difference likely results from distinct biological and disease initiation and progression events associated with Chr1- and Chr10-directed AMD.

Evaluation of the subfoveal choroidal and outer retinal layer thickness in obese women

CLINICAL RELEVANCE

Obesity has become one of the most important health problems of today with its increasing prevalence. With the development of retinal imaging systems, obesity has been observed to be associated with changes in outer retinal layers and choroid in women.

BACKGROUND

The aim of this study was to examine retinal layer parameters and their relationship with body mass index in obese women.

METHODS

The study included 197 eyes of 197 women, of whom 44 were normal-weight, 40 were overweight, 40 were class 1 obese, 38 were class 2 obese, and 35 were morbidly obese. The thickness of the choroid was measured manually using an enhanced-depth imaging optical coherence tomography scanning program.

RESULTS

The mean choroidal thickness values in five locations were lower than those of normal-weight, overweight, class 1, and class 2 obese women, in morbidly obese women (p < 0.05 for all). Subfoveal outer retinal layer thickness and specific sublayer thickness of the photoreceptor layer values were significantly lower in morbidly obese women than in normal-weight women, but there were no statistically significant differences between the groups in retinal pigment epithelium thickness and Bruch's membrane thickness (p = 0.001, p < 0.001, p = 1.00, and p = 0.101, respectively). Furthermore, there were significant negative relationships between body mass index and subfoveal choroidal thickness, subfoveal outer retinal layer thickness, and specific sublayer thickness of the photoreceptor layer values (r = -0.327, p < 0.001; r = -0.259, p < 0.001; and r = -0.281, p < 0.001, respectively).

CONCLUSIONS

Morbid obesity was associated with a thinner choroid, subfoveal outer retinal layer, and specific sublayer thickness of the photoreceptor layer in women. Furthermore, retinal hypoxia associated with morbid obesity may be related to a decrease in photoreceptor layer thickness. Thinning of the outer retinal layer may also lead to atrophy of the cone sheath.

Longitudinal Changes in Ganglion Cell-Inner Plexiform Layer of Fellow Eyes in Unilateral Neovascular Age-Related Macular Degeneration

PURPOSE

To determine longitudinal changes in the ganglion cell-inner plexiform layer (GC-IPL) thickness of the fellow eyes of patients with neovascular age-related macular degeneration (AMD).

DESIGN

Prospective cohort study.

METHODS

Patients with unilateral neovascular AMD, unilateral polypoidal choroidal vasculopathy (PCV), and control subjects were included. After the initial visit, GC-IPL thickness was measured twice more with at least a 1-year interval between examinations using spectral domain optical coherence tomography.

RESULTS

Twenty-seven fellow eyes of patients with unilateral choroidal neovascularization (CNV), 33 fellow eyes of patients with unilateral PCV, and 35 eyes of control subjects were enrolled. The GC-IPL thickness of the fellow eyes was 78.41 ± 9.23, 81.20 ± 5.52, and 81.60 ± 3.83 μm in the CNV, PCV, and control groups, respectively, and they showed a significant change over time (P < .001, P = .001, and P = .003, respectively). The reduction rate of GC-IPL thickness was -0.88, -0.41, and -0.31 μm per year in the fellow eyes of the CNV, PCV, and control groups, respectively (CNV > PCV, control, P < .001). In a linear mixed model determination of factors associated with GC-IPL reduction in the fellow eyes of the CNV group, the interaction between baseline GC-IPL thickness and duration showed a significant result (P < .001).

CONCLUSIONS

The fellow eyes of patients with neovascular AMD showed a greater reduction rate of GC-IPL thickness compared with fellow eyes of patients with unilateral PCV and control subjects. In patients with unilateral neovascular AMD, fellow eyes with a thicker GC-IPL at baseline showed a greater reduction in GC-IPL thickness over time.

Outer Retinal Layers' Thickness Changes in relation to Age and Choroidal Thickness in Normal Eyes

PURPOSE

To identify and correlate age-related changes in outer retinal layers' thickness and choroidal thickness (CT) in the normal eyes using spectral-domain optical coherence tomography (SD-OCT) and to investigate factors affecting these changes.

STUDY DESIGN

Observational cross-sectional study.

SUBJECTS AND METHODS

We studied 125 healthy Egyptians between 20 and 79 years old. Patients were divided into 3 groups: group 1 (20-40 years), group 2 (40-60 years), and group 3 (>60 years). All patients had full ophthalmic examination. SD-OCT was done to measure the 9 ETDRS macular grid sectors of retinal pigment epithelium and photoreceptor outer segment (RPE-OS), outer nuclear layer and photoreceptor inner segment (ONL-IS), and choroidal thickness (CT) (by enhanced depth imaging).

RESULTS

RPE-OS was significantly thinner in group 3 than in the other 2 groups (central: P < 0.001). Moreover, the 3 groups were significantly different from each other regarding the CT (central: P < 0.001); significant thinning was noticed in the choroid with age. The 3 groups did not show significant difference concerning the ONL-IS thickness. RPE-OS and CT showed statistically significant negative correlation with age (central RPE-OS: r = -0 C.345, P < 0.001, and central CT: r = -0.725, P < 0.001) while ONL-IS showed statistically nonsignificant correlation with age (central ONL-IS: r = -0.08, P=0.376). Multiple regression analysis revealed that the most important determinant of central 1 mm RPE-OS thickness in this study was age (β = -0.087, P=0.010) rather than choroidal thinning (β = 0.001, P=0.879).

CONCLUSION

RPE-OS layer thickness shows significant thinning with increasing age, and with decrease in CT, however, age is the most determinant factor of this thinning.

Normative pattern and determinants of outer retinal thickness in an Asian population: the Singapore Epidemiology of Eye Diseases Study

BACKGROUND/AIMS

To evaluate the distribution and determinants of outer retinal thickness in eyes without retinal diseases, using spectral-domain optical coherence tomography (SD-OCT).

METHODS

Participants were recruited from the Singapore Epidemiology of Eye Diseases Study, a population-based study among Chinese, Malays and Indians in Singapore. A total of 5333 participants underwent SD-OCT imaging in which a 6×6 mm² measurement area centred at the fovea. Outer retinal thickness was defined as the distance from the outer plexiform layer to the retinal pigment epithelium layer boundary.

RESULTS

7444 eyes from 4454 participants were included in final analysis. Of them, mean age was 58.4 years (SD 8.3), and 2294 (51.5%) were women. Women (121.0±8.1 µm) had thinner average outer retinal thickness than men (125.6±8.2 µm) (p<0.001). Malays (121.4±8.7 µm) had thinner average outer retinal thickness than Indians (124.3±8.6 µm) and Chinese (123.7±7.9 µm) (both p<0.001). In multivariable models, thinner average outer retinal thickness was associated with older age (per decade, β=-1.02, p<0.001), hypertension (β=-0.59, p=0.029), diabetes (β=-0.73, p=0.013), chronic kidney disease (β=-1.25, p=0.017), longer axial length (per mm, β=-0.76, p<0.001), flatter corneal curvature (per mm, β=-2.00, p<0.001) and higher signal strength (β=-1.46, p<0.001).

CONCLUSION

In this large sample of Asian population, we provided normative SD-OCT data on outer retinal thickness in eyes without retinal diseases. Women had thinner outer retina than men. For the first time, these findings provide fundamental knowledge on normative profile of outer retinal thickness in Asians.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

Purpose

To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects.

Methods

Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI).

Results

Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05).

Conclusions

During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components.

Regeneration of Photoreceptor Outer Segments After Scleral Buckling Surgery for Rhegmatogenous Retinal Detachment

PURPOSE

To investigate the regeneration of the cone outer segments in eyes after surgery for fovea-off rhegmatogenous retinal detachment with an adaptive optics (AO) fundus camera and to correlate these findings with the findings of optical coherence tomography (OCT).

DESIGN

Retrospective, observational case series.

METHODS

Medical charts of 21 eyes of 21 patients who had undergone surgery for fovea-off rhegmatogenous retinal detachment were retrospectively studied. Cone mosaic images were obtained with an AO fundus camera. Cone packing density at 2 degrees from the fovea within the previously detached area was measured 6 and 12 months after surgery. Retinal thicknesses between the interdigitation zone and the retinal pigment epithelium (IZ-RPE) and between the ellipsoid zone and the retinal pigment epithelium (EZ-RPE) were measured in OCT images.

RESULTS

Cone density 12 months after surgery was significantly increased from that at 6 months (P = .001), but was still significantly lower than that of normal fellow eyes (P < .001). IZ-RPE and EZ-RPE thickness significantly increased from 6 to 12 months (P = .045, P = .033, respectively), and these values were not significantly different from those of normal fellow eyes. Multivariate analysis showed that cone density at 12 months was significantly associated with IZ-RPE thickness (P = .002), and increases in cone packing density were significantly associated with increases in IZ-RPE thickness (P = .001).

CONCLUSIONS

Recovery of cone packing density measured by AO was associated with structural recovery of the outer retina observed in OCT, suggesting regeneration of the photoreceptor outer segment after surgery.