Rates of Ganglion Cell-Inner Plexiform Layer Thinning in Normal, Open-Angle Glaucoma and Pseudoexfoliation Glaucoma Eyes: A Trend-Based Analysis

Comparing corneal biomechanical parameters between primary open-angle glaucoma and pseudoexfoliation glaucoma using corvis ST

BACKGROUND

To compare corneal biomechanical properties between primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) using CorVis ST.

METHODS

Thirty-three eyes of 33 patients with PXG and 29 eyes of 29 patients with POAG were enrolled in this cross-sectional study. All eyes underwent CorVis ST. Biomechanical parameters at the first and second applanation and highest concavity were measured. Man-Whitney U test and stepwise linear regression were used to compare the parameters between groups.

RESULTS

The mean age was 67.1 ± 7.9 and 70.3 ± 7.1 years in the POAG and PXG groups, respectively (P = 0.072). Eighteen patients in each group were male (P = 0.549). Intraocular pressure (IOP) measured by Goldmann applanation tonometry was not different between groups (P = 0.112) while the PXG group had higher biomechanically corrected IOP (14.3 ± 3.5 mmHg vs. 15.9 ± 3.4 mmHg; P = 0.042). Central corneal thickness was lower in the PXG group (546 ± 29 μm vs. 523 ± 37 μm; P = 0.008). A2 velocity was lower in the PXG group (P = 0.008). The highest concavity (HC) deformation amplitude and deflection length and peak distance were lower in the PXG group (p < 0.05). The PXG eyes had a higher stress-strain index (1.29 ± 0.26 vs. 1.42 ± 0.27; P = 0.022).

CONCLUSION

The results of the current investigation are in favor of the presence of a stiffer cornea in the PXG group.

Corneal endothelial and retinal microvascular changes in pseudoexfoliation syndrome: insights from specular microscopy and OCT angiography

PURPOSE

To investigate the correlation between corneal specular microscopy (SM) and macular optical coherence tomography angiography (OCTA) data in patients with pseudoexfoliation syndrome (PXS).

METHODS

This was a cross-sectional, prospective study. Consecutive patients aged > 45 years with PXS or normal examination results were included. We examined cell density (CD), average cell area (AVG), coefficient of variation (CV), and hexagonality values from the SM. We collected 6 × 6 mm macular OCTA data with a quality score of 6/10 or higher.

RESULTS

Thirty-five eyes with PXS and 32 healthy eyes were evaluated. The CD, AVG, CV, and hexagonality for the PXS group were 2388.5 ± 368.8 cell/mm2, 435.0 ± 117.6 µm2, 28.9 ± 4.8%, and 67.6 ± 4.8%, respectively. The control group had the following values for CD, AVG, CV, and hexagonality: 2654.5 ± 269.8 cell/mm2, 380.4 ± 38.8 µm2, 29.8 ± 5.1%, and 67.1 ± 4.9%, respectively. No correlation was observed between OCTA and SM findings in the PXS group. We found a slight but significant link between CD and OCTA outer and total field estimations in the control group (p = 0.03 r = -0.25 and p = 0.02, r = 0.27, respectively). AVG and OCTA data in the control group indicated an association in the outer- and full-field analyses (p = 0.03 r = 0.25, p = 0.02, r = 0.27, respectively).

CONCLUSION

Highlighting the observed lack of correlation between SM and macular OCTA findings in PXS patients in this study emphasizes the necessity of prioritizing early detection of anterior segment changes. The results indicate that immediate monitoring and intervention could reduce undesired consequences and maintain visual function in those affected.

Comparison of glaucoma progression rate in glaucoma patients at different stages using guided progression analysis with optical coherence tomography

BACKGROUND

The aim of the present study was to compare the rates of change in Ganglion Cell- Inner Plexiform Layer (GCIPL) and Retinal Nerve Fiber Layer (RNFL) thickness, as measured by Optical Coherence Tomography (OCT) Guided Progression Analysis (GPA) program in control group, Primary Open Angle Glaucoma (POAG) and Pseudoexfoliation Glaucoma (PXG) eyes.

METHODS

60 POAG and 60 PXG patients and 30 control group patients were included in the study. Patients diagnosed with glaucoma were divided into two groups as mild (Mean deviation (MD) > -6.00) and moderate-severe (MD < -6.00). The average, superior and inferior quadrant thinning rates (expressed in micrometers per year) of GCIPL and RNFL in the OCT GPA program were compared between groups.

RESULTS

Average GCIPL thinning rates were -0.23 ± 0.21 μm/year in the control group, -0.64 ± 0.54 μm/year in POAG patients, and -1.06 ± 1.16 μm/year in PXG patients (ANOVA, p < 0.001). Average RNFL thinning rates were -0.33 ± 0.44 μm/year in the control group, -0.86 ± 0.73 μm/year in POAG patients, and -1.33 ± 1.4 μm/year in PXG patients (ANOVA, p < 0.001).

CONCLUSIONS

The rates of GCIPL and RNFL thinning were highest in patients with PXG. We found that the glaucoma stage did not affect the rate of RNFL and GCIPL thinning.

Number of macula optical coherence tomography scans needed to detect glaucoma progression

BACKGROUND

To evaluate the impact of testing frequency on the time required to detect statistically significant glaucoma progression for ganglion cell complex (GCC) with optical coherence tomography (OCT).

MATERIALS AND METHODS

From multicentre glaucoma registries, 332 eyes of 201 glaucoma patients were enrolled over an average of 4.4 years. Patients with 4 or more OCT tests were selected to calculate the longitudinal rates of GCC thickness change over time by linear regression. A computer simulation was then used to generate real-world GCC data and assess the time required to detect progression at different loss rates and testing frequencies based on variability estimates. Time and accuracy to detect worsening of progression were calculated.

RESULTS

As testing frequency increased, the time required to detect a statistically significant negative GCC slope decreased, but not proportionally. All eyes with a GCC loss of -1 µm/year progressed after 3.8, 2.6 and 2.2 years on average when testing was conducted one, two and three times per year, respectively. For eyes with a GCC loss of -1.5 µm/year, progression was identified after 3.3, 2.2, and 1.8 years on average, respectively.

CONCLUSION

Increasing the frequency of macular OCT testing to three times per year more sensitively detects progression compared with two times per year. However, two times per year testing may be sufficient in clinical settings to detect progression and also to reduce the healthcare burden.

TRIAL REGISTRATION NUMBERS

NCT00221897, NCT00221923.

Racial-ethnic disparities in concurrent rates of peripapillary & macular OCT parameters among a large glaucomatous clinical population

OBJECTIVES

To compare rates of change in peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) parameters among different race-ethnicities from a large electronic health record database of subjects with or suspected of glaucoma.

METHODS

In this retrospective cohort study, rates of change were obtained using joint longitudinal linear mixed models for eyes with ≥3 visits and ≥1 year of follow-up, adjusting for age, sex, intraocular pressure, central corneal thickness, and baseline pRNFL and mGCIPL thickness. Best linear unbiased predictor estimates of various parameters were stratified by baseline glaucoma severity and analysed by racial-ethnic group.

RESULTS

A total of 21,472 spectral domain optical coherence tomography (OCT) pRNFL scans and 14,431 mGCIPL scans from 2002 eyes were evaluated. A total of 200 (15.6%) and 601 (46.8%) subjects identified as non-Hispanic Black (NHB) and Hispanic, respectively. NHB eyes exhibited faster rates of change in pRNFL among glaucoma suspect (global pRNFL -0.57 ± 0.55 µm/year vs. -0.37 ± 0.62 µm/year among Hispanics, p < 0.001), mild glaucoma (superior pRNFL quadrant -1.20 ± 1.06 µm/year vs. -0.75 ± 1.51 µm/year among non-Hispanic Whites (NHW), p = 0.043), and moderate glaucoma eyes (superior pRNFL quadrant -1.31 ± 1.49 µm/year vs. -0.52 ± 1.26 µm/year among Hispanics, p = 0.003). NHB eyes exhibited faster rates of mGCIPL loss corresponding to pRNFL rates. Global pRNFL and mGCIPL rates were strongly correlated (R2 = 0.70).

CONCLUSIONS

Adjusted rates of pRNFL and mGCIPL loss significantly differed between racial-ethnic groups when stratified by glaucoma severity, with faster rates among NHB patients. These differences highlight key racial-ethnic disparities in adjusted rates of glaucoma OCT parameters.

Long-Term Rate of Optic Disc Rim Loss in Glaucoma Patients Measured From Optic Disc Photographs With a Deep Neural Network

Purpose

This study uses deep neural network-generated rim-to-disc area ratio (RADAR) measurements and the disc damage likelihood scale (DDLS) to measure the rate of optic disc rim loss in a large cohort of glaucoma patients.

Methods

A deep neural network was used to calculate RADAR and DDLS for each optic disc photograph (ODP). Patient demographics, diagnosis, intraocular pressure (IOP), and mean deviation (MD) from perimetry were analyzed as risk factors for faster progression of RADAR. Receiver operating characteristic (ROC) curves were used to compare RADAR and DDLS in their utility to distinguish glaucoma from glaucoma suspect (GS) and for detecting glaucoma progression.

Results

A total of 13,679 ODPs with evidence of glaucomatous optic nerve damage from 4106 eyes of 2407 patients with glaucoma or GS were included. Of these eyes, 3264 (79.5%) had a diagnosis of glaucoma, and 842 (20.5%) eyes were GS. Mean ± SD baseline RADAR of GS and glaucoma were 0.67 ± 0.13 and 0.57 ± 0.18, respectively (P < 0.001). Older age, greater IOP fluctuation, baseline MD, right eye, and diagnosis of secondary open-angle glaucoma were associated with slope of RADAR. The mean baseline DDLS of GS and glaucoma were 3.78 and 4.39, respectively. Both RADAR and DDLS showed a less steep slope in advanced glaucoma. In glaucoma, the change of RADAR and DDLS correlated with the corresponding change in MD. RADAR and DDLS had a similar ability to discriminate glaucoma from GS and detect disease progression. Area under the ROC curve of RADAR and DDLS was 0.658 and 0.648.

Conclusions

Automated calculation of RADAR and DDLS with a neural network can be used to evaluate the extent and long-term rate of optic disc rim loss and is further evidence of long-term nerve fiber loss in treated patients with glaucoma.

Translational Relevance

Our study provides a large clinic-based experience for RADAR and DDLS measurements in GS and glaucoma with a neural network.

Comparison of Patterns of Structural Progression in Primary Open Angle Glaucoma and Pseudoexfoliation Glaucoma

PRCIS

Primary open angle glaucoma and pseudoexfoliation glaucoma showed different progression patterns of the retinal nerve fiber layer and ganglion cell-inner plexiform layer thinning in OCT-guided progression analysis.

PURPOSE

To compare the patterns of progression of retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thinning by guided progression analysis (GPA) of optical coherence tomography (OCT) in primary open angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG).

MATERIALS AND METHODS

The progression of RNFL and GCIPL thinning was assessed by the GPA of Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). By overlaying the acquired images of the RNFL and GCIPL thickness-change maps, the topographic patterns of progressive RNFL and GCIPL thinning were evaluated. The rates of progression of RNFL and GCIPL thinning were analyzed and compared between patients with POAG and those with PXG.

RESULTS

Of the 248 eyes of 248 patients with POAG (175 eyes of 175 patients) or PXG (73 eyes of 73 patients) enrolled, 156 POAG eyes and 48 PXG eyes were included. Progressive RNFL thinning was significantly more common in PXG than in POAG ( P =0.005). According to the RNFL progression-frequency maps, progression appeared mainly in the superotemporal and inferotemporal areas in POAG, whereas it had invaded more into the temporal area in PXG. According to the GCIPL maps, progression was most common in the inferotemporal area in both POAG and PXG. The average progression rate of GCIPL thinning was faster in PXG than in POAG ( P =0.013), and when analyzed in 2 halves (superior/inferior), the progression rate of the inferior half was faster in PXG than in POAG ( P =0.011).

CONCLUSIONS

OCT GPA showed progression patterns of RNFL and GCIPL thinning in POAG and PXG. Understanding the specific patterns of progressive RNFL and GCIPL thinning according to glaucoma type may prove helpful to glaucoma-patient treatment and monitoring.

Intraocular Pressure and Rates of Macular Thinning in Glaucoma

PURPOSE

To evaluate the effect of intraocular pressure (IOP) on the rates of macular thickness (ganglion cell layer [GCL] and ganglion cell-inner plexiform layer [GCIPL]) change over time measured by spectral-domain (SD) OCT.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Overall, 451 eyes of 256 patients with primary open-angle glaucoma.

METHODS

Data were extracted from the Duke Ophthalmic Registry, a database of electronic medical records of patients observed under routine clinical care at the Duke Eye Center, and satellite clinics. All records from patients with a minimum of 6 months of follow-up and at least 2 good-quality Spectralis SD-OCT macula scans were included. Linear mixed models were used to investigate the relationship between average IOP during follow-up and rates of GCL and GCIPL thickness change over time.

MAIN OUTCOME MEASURES

The effect of IOP on the rates of GCL and GCIPL thickness loss measured by SD-OCT.

RESULTS

Eyes had a mean follow-up of 1.8 ± 1.3 years, ranging from 0.5 to 10.2 years. The average rate of change for GCL thickness was -0.220 μm/year (95% confidence interval [CI], -0.268 to -0.172 μm/year) and for GCIPL thickness was -0.231 μm/year (95% CI, -0.302 to -0.160 μm/year). Each 1-mmHg higher mean IOP during follow-up was associated with an additional loss of -0.021 μm/year of GCL thickness (P = 0.001) and -0.032 μm/year of GCIPL thickness (P = 0.001) after adjusting for potentially confounding factors, such as baseline age, disease severity, sex, race, central corneal thickness, and follow-up time.

CONCLUSIONS

Higher IOP was significantly associated with faster rates of GCL and GCIPL loss over time measured by SD-OCT, even during relatively short follow-up times. These findings support the use of SD-OCT GCL and GCIPL thickness measurements as structural biomarkers for the evaluation of the efficacy of IOP-lowering therapies in slowing down the progression of glaucoma.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Ganglion Cell Complex Analysis: Correlations with Retinal Nerve Fiber Layer on Optical Coherence Tomography

The aim of this review is to analyze the correlations between the changes in the ganglion cell complex (GCC) and the retinal nerve fiber layer (RNFL) on optical coherence tomography in different possible situations, especially in eyes with glaucoma. For glaucoma evaluation, several studies have suggested that in the early stages, GCC analysis, especially the thickness of the infero and that of the inferotemporal GCC layers, is a more sensitive examination than circumpapillary RNFL (pRNFL). In the moderate stages of glaucoma, inferior pRNFL thinning is better correlated with the disease than in advanced cases. Another strategy for glaucoma detection is to find any asymmetry of the ganglion cell-inner plexiform layers (GCIPL) between the two macular hemifields, because this finding is a valuable indicator for preperimetric glaucoma, better than the RNFL thickness or the absolute thickness parameters of GCIPL. In preperimetric and suspected glaucoma, GCC and pRNFL have better specificity and are superior to the visual field. In advanced stages, pRNFL and later, GCC reach the floor effect. Therefore, in this stage, it is more useful to evaluate the visual field for monitoring the progression of glaucoma. In conclusion, GCC and pRNFL are parameters that can be used for glaucoma diagnosis and monitoring of the progression of the disease, with each having a higher accuracy depending on the stage of the disease.

Glaucoma progression. Clinical practice guide

OBJECTIVE

To provide general recommendations that serve as a guide for the evaluation and management of glaucomatous progression in daily clinical practice based on the existing quality of clinical evidence.

METHODS

After defining the objectives and scope of the guide, the working group was formed and structured clinical questions were formulated following the PICO (Patient, Intervention, Comparison, Outcomes) format. Once all the existing clinical evidence had been independently evaluated with the AMSTAR 2 (Assessment of Multiple Systematic Reviews) and Cochrane "Risk of bias" tools by at least two reviewers, recommendations were formulated following the Scottish Intercollegiate Guideline network (SIGN) methodology.

RESULTS

Recommendations with their corresponding levels of evidence that may be useful in the interpretation and decision-making related to the different methods for the detection of glaucomatous progression are presented.

CONCLUSIONS

Despite the fact that for many of the questions the level of scientific evidence available is not very high, this clinical practice guideline offers an updated review of the different existing aspects related to the evaluation and management of glaucomatous progression.

Evaluation of Anterior Segment Parameters in Pseudoexfoliation Disease Using Anterior Segment Optical Coherence Tomography

PURPOSE

To compare anterior segment and angle parameters between pseudoexfoliation syndrome (PEX) and PEX glaucoma (PEXG) and normal control subjects using anterior segment optical coherence tomography (AS-OCT) imaging.

DESIGN

Cross-sectional study.

METHODS

One hundred and two subjects with PEXG, PEX, and normal eyes as the control group were recruited from an academic referral institution. All subjects underwent a complete ophthalmologic examination, axial length measurement, and AS-OCT imaging. Anterior segment and angle parameters were evaluated.

RESULTS

After excluding 4 eyes because of poor imaging of the scleral spur, data from 34 eyes with PEXG, 33 eyes with PEX, and 31 eyes of normal control subjects were analyzed. Anterior chamber depth was significantly shallower in eyes with PEXG compared with eyes of control subjects (P < .001). The differences in anterior chamber angle parameters (AOD500, AOD750, TISA500,and TISA750) were significant among study groups, with lower values in the PEXG group compared with the PEX and control subject groups. Lens vault (mean [mm]±SD) was higher in the PEXG (0.46 ±0.21) and PEX (0.427 +0.28) groups compared with the control group (0.305+ 0.20).

CONCLUSIONS

PEXG eyes have the narrowest anterior chamber angle parameters. There is a progressive decrease in angle parameters from control subjects to the PEX group to the PEXG group. Narrow anterior chamber angle and anterior chamber depth may have a role in the progression of PEX to PEXG. Detection of narrow angle in these patients may help clinicians manage the disease more properly.

Ganglion cell complex and macular thickness layers in primary open-angle glaucoma, pseudoexfoliation glaucoma and healthy eyes: A comparative study

PURPOSE

To investigate the differences in the ganglion cell complex (GCC) and macular thickness measurements between primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG), and healthy eyes with optical coherence tomography (OCT)optovue.

METHODS

In this non-randomized comparative cross-sectional study, 43 healthy eyes, 68 POAG eyes, and 57 PXG eyes were included. Patients were matched for age and disease severity. OCT angiography images were obtained for automated measurement of the GCC and macular thickness layers (inner and outer).

RESULTS

All GCC parameters were significantly difference between healthy and glaucomatous eyes (mild, and moderate to severe disease).There were no significant differences in GCC parameters between POAG and PXG patients except focal loss volume (FLV) after adjustment. Moderate to severe PXG eyes exhibited significantly lower GCC, larger global loss volume (GLV) values, and FLV values when compared with mild PXG eyes (p<= 0.05). We found significant thinning patterns in inner retinal thickness (fovea, parafovea, and perifovea), and total retinal thickness (parafovea, and perifovea) in moderate to severe PXG eyes when comparing with POAG eyes. Patients with moderate to severe PXG also showed significantly thinning patterns in inner retinal layers (fovea, parafovea and perifovea) and total retinal thickness (nasal parafovea) in compared to mild PXG.

CONCLUSION

It appears that GCC thickness is not significantly different between POAG and PXG except FLV. Despite similar retinal thickness in mild disease, a significant reduction in total and inner retinal thickness was demonstrated in moderate to severe PXG compared to moderate to severe POAG, in fovea, parafovea and perifovea region.

Effects of prolonged type 2 diabetes on changes in peripapillary retinal nerve fiber layer thickness in diabetic eyes without clinical diabetic retinopathy

To identify the effects of prolonged type 2 diabetes (T2DM) on changes in peripapillary retinal nerve fiber layer (pRNFL) thickness in patients without clinical diabetic retinopathy. Subjects were divided into two groups: controls and patients with T2DM (DM group). After the initial visits, the pRNFL thicknesses were measured three more times at 1-year intervals. Subgroup analyses were performed in patients with T2DM duration ≥ 10 years. The mean pRNFL thickness at each visit was 95.8 ± 8.1, 95.4 ± 8.3, 94.9 ± 8.1, and 94.5 ± 8.3 μm in the control group (P = 0.138) (n = 55); and 93.4 ± 9.1, 92.1 ± 9.3, 90.9 ± 9.3, and 89.5 ± 9.2 μm in the DM group (P < 0.001) (n = 85). The estimated rate of reduction in mean pRNFL thickness was - 0.45 μm/year in the control group and - 1.34 μm/year in the DM group, respectively. In the DM group, the BCVA and HbA1c (both P = 0.001) were significant factors associated with pRNFL reduction. In patients with T2DM duration ≥ 10 years, the estimated pRNFL reduction rate was - 1.61 μm/year, and hypertension was a significant factor affecting the pRNFL reduction (P = 0.046). We confirmed rapid pRNFL reduction over time in T2DM, and the reduction rate was higher in patients with T2DM ≥ 10 years. Additionally, BCVA and HbA1c levels were significantly associated with the change in pRNFL thickness in T2DM patients.

Utilisation of poor-quality optical coherence tomography scans: adjustment algorithm from the Singapore Epidemiology of Eye Diseases (SEED) study

PURPOSE

To evaluate the effect of signal strength (SS) on optical coherence tomography (OCT) parameters, and devise an algorithm to adjust the effect, when acceptable SS cannot be obtained.

METHODS

5085 individuals (9582 eyes), aged ≥40 years from the Singapore Epidemiology of Eye Diseases population-based study were included. Everyone underwent a standardised ocular examination and imaging with Cirrus HD-OCT. Effect of SS was evaluated using multiple structural breaks linear mixed-effect models. Expected change for increment in SS between 4 and 10 for individual parameter was calculated. Subsequently we devised and evaluated an algorithm to adjust OCT parameters to higher SS.

RESULTS

Average retinal nerve fibre layer (RNFL) thickness showed shift of 4.11 µm from SS of 5 to 6. Above 6, it increased by 1.72 and 3.35 µm to 7 and 8; and by 1.09 µm (per unit increase) above 8 SS. Average ganglion cell-inner plexiform layer (GCIPL) thickness shifted 5.15 µm from SS of 5 to 6. Above 6, increased by 0.94 µm from 7 to 8; and by 0.16 µm (per unit increase) above 8 SS. When compared with reference in an independent test set, the algorithm produced less systemic bias. Algorithm-adjusted average RNFL was 0.549 µm thinner than the reference, while the unadjusted one was 2.841 µm thinner (p<0.001). Algorithm-adjusted and unadjusted average GCIPL was 1.102 µm and 2.228 µm thinner (p<0.001).

CONCLUSIONS

OCT parameters can be adjusted for poor SS using an algorithm. This can potentially assist in diagnosis and monitoring of glaucoma when scans with acceptable SS cannot be acquired from patients in clinics.

Macular imaging with optical coherence tomography in glaucoma

With the advent of spectral-domain optical coherence tomography, imaging of the posterior segment of the eye can be carried out rapidly at multiple anatomical locations, including the optic nerve head, circumpapillary retinal nerve fiber layer, and macula. There is now ample evidence to support the role of spectral-domain optical coherence tomography imaging of the macula for detection of early glaucoma. Macular spectral-domain optical coherence tomography measurements demonstrate high reproducibility, and evidence on its utility for detection of glaucoma progression is accumulating. We present a comprehensive review of macular spectral-domain optical coherence tomography imaging emerging as an essential diagnostic tool in glaucoma.

Effect of Intravitreal Injections on Retinal Imaging Metrics in Glaucomatous and Non-Glaucomatous Eyes

Purpose of Review

To summarize the available literature on retinal imaging metrics in the context of intravitreal injections in glaucomatous and non-glaucomatous eyes.

Recent Findings

The retinal nerve fiber layer (RNFL) in injected non-glaucomatous eyes appears to thin at a similar rate to uninjected fellow eyes. A total of four studies evaluating RNFL thinning in injected glaucomatous eyes yielded mixed results, with more recent longitudinal investigations suggesting a potential association. The ganglion cell-inner plexiform layer is also being studied as a potential endpoint in both glaucomatous and non-glaucomatous eyes following intravitreal injections.

Profiles of Ganglion Cell-Inner Plexiform Layer Thickness in a Multi-Ethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study

PURPOSE

To examine the normative profile and determinants of macular ganglion cell-inner plexiform layer (GCIPL) thickness based on spectral-domain OCT (SD-OCT) in a nonglaucoma, multi-ethnic Asian population.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

Ethnic Chinese, Malay, and Indian adults aged ≥40 years recruited from the Singapore Epidemiology of Eye Diseases Study.

METHODS

All participants underwent standardized examinations. The GCIPL thickness was measured using Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA). Participants with glaucoma or poor-quality scans were excluded. Eye-specific data were used. Associations of ocular and systemic factors with GCIPL thickness parameters were investigated using multivariable linear regression with generalized estimating equation models to account for correlation between both eyes.

MAIN OUTCOME MEASURES

GCIPL thickness.

RESULTS

A total of 4464 participants (7520 eyes) consisting of 1625 Chinese, 1212 Malay, and 1627 Indian adults contributed to this analysis. Average GCIPL thickness was 82.6±6.1 μm in Chinese, 81.5±6.8 μm in Malays, and 78.0±6.9 μm in Indians (P < 0.001 by analysis of variance). The 5th percentile limit of average GCIPL thickness was 72 μm in Chinese, 70 μm in Malays, and 67 μm in Indians. In multivariable analysis adjusting for age, gender, axial length, presence of cataract, OCT signal strength, disc area, hypertension, diabetes, and hyperlipidemia, eyes of Indians were observed to have 3.43 μm thinner GCIPL on average compared with Chinese (P < 0.001) and 3.36 μm thinner GCIPL compared with Malays (P < 0.001). In addition, older age (per decade; β = -2.51), female (β = -1.57), longer axial length (per mm; β = -1.54), and presence of chronic kidney disease (β = -1.49) were significantly associated with thinner average GCIPL (all P ≤ 0.008). Larger optic disc area (per mm²; β = 0.78; P < 0.001) was associated with thicker GCIPL. These factors were consistently observed to be significant for superior and inferior hemisphere GCIPL thickness.

CONCLUSIONS

GCIPL thickness profiles were significantly thinner in Indians compared with Chinese and Malays. Our findings further highlight the need of a more refined, ethnic-specific normative database for GCIPL thickness, which in turn may improve the detection and diagnosis of glaucoma in Asians.

Ganglion Cell - Inner Plexiform Layer Damage in Diabetic Patients: 3-Year Prospective, Longitudinal, Observational Study

Diabetes is expected to accelerate age-related ganglion cell–inner plexiform layer (GC-IPL) loss, but there is limited information on the rate of reduction in GC-IPL thicknesses. We aimed to evaluate the reduction rate of GC-IPL thickness in diabetic patients, and to compare the rates between patients without and with diabetic retinopathy (DR). We included 112 eyes of 112 patients with diabetes [49 eyes without DR (no-DR group) and 63 eyes with mild to moderate non-proliferative DR (NPDR group)] and 63 eyes of 63 normal controls (control group) in this study. Macular GC-IPL thickness in all participants was measured for 3 years at 1-year intervals. The reduction rates of GC-IPL thickness were determined by linear mixed models and compared among the three groups. The estimated reduction rates of the average GC-IPL thickness in the no-DR (−0.627 μm/year) and NPDR (−0.987 μm/year) groups were 2.26-fold (p = 0.010) and 3.56-fold (p = 0.001) faster, respectively, than the control group (−0.277 μm/year). Age, duration of diabetes, and baseline average GC-IPL thickness were associated with longitudinal changes in average GC-IPL thickness. The GC-IPL reduction rate was significantly faster in diabetic patients, with and without DR. Physicians should therefore be aware that GC-IPL damage continues even if there is no DR.

Thinning rates of retinal nerve layer and ganglion cell-inner plexiform layer in various stages of normal tension glaucoma

AIMS

To compare the changes in the macular retinal nerve fibre layer (mRNFL), macular ganglion cell layer and inner plexiform layer (mGCIPL), and circumpapillary retinal nerve fibre layer (cpRNFL) in various stages of normal tension glaucoma (NTG) using spectral domain optical coherence tomography.

METHODS

Eyes with NTG (n=218) were assigned into three groups based on initial mean deviation (MD) as follows: mild (MD>-6 dB), moderate (-6 dB≥MD≥-12 dB) and severe (-12 dB>MD>-20 dB). Annual rates of change in mRNFL, mGCIPL and cpRNFL thickness were calculated by linear regression analysis.

RESULTS

Age, gender, spherical equivalent, and average intraocular pressure during follow-up were not significantly different among the three groups. There were significant differences in the mRNFL, mGCIPL and cpRNFL among the three groups at baseline (p<0.0001 in all sectors except for the mRNFL in the superonasal sector). The average thinning rates of the mRNFL, mGCIPL and cpRNFL were -0.38±0.32 µm/year, -0.62±0.46 µm/year and -0.86±0.83 µm/year, respectively. No significant difference in the rates of change in the mRNFL and mGCIPL were found among the groups in any sector. However, there was a significant difference in the rate of change in the cpRNFL among the groups (in all sectors: p<0.0001).

CONCLUSIONS

Changes in the mRNFL and mGCIPL can reflect the progression of NTG even in its advanced stage. However, careful interpretation of changes in the cpRNFL in the advanced stage of glaucoma is warranted due to a potential floor effect.

Longitudinal Changes in the Peripapillary Retinal Nerve Fiber Layer Thickness of Patients With Type 2 Diabetes

Importance

Type 2 diabetes is expected to accelerate age-related peripapillary retinal nerve fiber layer (pRNFL) loss, but limited information on the rate of reduction in pRNFL thicknesses in patients with type 2 diabetes is available.

Objective

To investigate longitudinal changes in pRNFL thickness in patients with type 2 diabetes, with or without diabetic retinopathy (DR).

Design, Setting, and Participants

A total of 164 eyes of 63 healthy individuals and 101 patients with type 2 diabetes (49 patients without DR [non-DR group] and 52 patients with mild to moderate nonproliferative DR [NPDR group]) were enrolled in this prospective, longitudinal, observational study from January 2, 2013, through February 27, 2015. Participants were followed up for 3 years, and the peripapillary mean and sector RNFL thicknesses were measured at 1-year intervals. The mean rate of pRNFL loss was estimated using a linear mixed model and compared among the 3 groups. Follow-up was completed on March 16, 2018, and data were analyzed from April 2 through July 27, 2018.

Exposure

Type 2 diabetes.

Main Outcomes and Measures

The rate of reduction in pRNFL thickness in patients with type 2 diabetes.

Results

A total of 164 participants (88 women [53.7%]; mean [SD] age, 58.2 [8.7] years) were included in the study analysis. The mean (SD) age of the control group was 56.5 (9.3) years (39 women [61.9%]); the non-DR group, 59.1 (9.4) years (26 women [53.1%]); and the NPDR group, 59.4 (11.0) years (23 women [44.2%]). Mean (SD) duration of type 2 diabetes was 7.1 (4.4) years in the non-DR group and 13.2 (8.4) years in the NPDR group. The baseline mean (SD) pRNFL thickness was 96.2 (11.0) μm in the control group, 93.5 (6.4) μm in the non-DR group, and 90.4 (7.9) μm in the NPDR group. During 3 years of follow-up, these values decreased to 95.0 (9.2) μm in the control group, 90.3 (6.4) in the non-DR group, and 86.6 (7.9) μm in the NPDR group. In a linear mixed model, the estimated mean pRNFL loss was -0.92 μm/y in the non-DR group (P < .001) and -1.16 μm/y in the NPDR group (P < .001), which was 2.9-fold (95% CI, 1.1-14.8; P = .003) and 3.3-fold (95% CI, 1.4-18.0; P < .001) greater, respectively, than that of the control group (-0.35 μm/y; P = .01).

Conclusions and Relevance

Progressive reduction of pRNFL thickness was observed in healthy controls and patients with type 2 diabetes without and with DR; however, type 2 diabetes was associated with a greater loss of pRNFL regardless of whether DR was present. These findings suggest that pRNFL loss may occur in people with type 2 diabetes even in the absence of DR progression.