Scanning laser polarimetry in myopic and hyperopic subjects

Effect of myopia and optic disc area on ganglion cell-inner plexiform layer and retinal nerve fiber layer thickness

Purpose:

The aim of this work was to study the impact of myopia and different optic disc areas on ganglion cell-inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) thickness profiles in myopic patients by spectral-domain optical coherence tomography (SD-OCT).

Methods:

This was a cross-sectional study of 100 eyes of 50 myopic individuals. All patients underwent complete ophthalmic evaluation and SD-OCT examination. According to spherical equivalent (SE), patients were divided into M1, M2, and M3 (low, moderate, and high myopia group). According to optic disc area values, patients were divided into D1, D2 and D3 (small, medium and large disc groups). Average GCIPL and RNFL thickness recorded globally and separately for all quadrants and also according to 12 clock hours and analyzed with respect to different myopic groups, optic disc area groups, and axial length.

Results:

Quadrantic RNFL thickness profiles and their average RNFL thickness were significantly thinner in high myopic group compared to low myopic group, except for the temporal quadrant (P < 0.05). Average RNFL and RNFL thickness of all quadrants were significantly thicker in the large disc group than in the small disc group (P < 0.05). Average GCIPL and GCIPL thicknesses of all sectors were significantly thinner in high myopic group compared to low myopic group (P < 0.05). No significant correlation was observed between GCIPL and disc area changes. Average RNFL thickness correlated significantly with SE (3.667 μm/diopter), axial length (–5.3805 μm/mm) and optic disc area (9.4617 μm/mm²). Also, average GCIPL thickness correlated statistically significantly with SE (1.6807 μm/diopter) and axial length (–2.626 μm/mm).

Conclusion:

Myopia and axial length significantly reduce RNFL and GCIPL thickness profiles but the optic disc area significantly increases RNFL thickness, but not GCIPL thickness.

An assessment of variation in macular volume and RNFL thickness in myopes using OCT and their significance for early diagnosis of primary open-angle glaucoma

PURPOSE

An assessment of variation in Macular Volume and RNFL Thickness in myopes using OCT, and their significance for early diagnosis of Primary Open Angle Glaucoma(POAG).

MATERIALS AND METHOD

Total of 122 eyes of 61 Indian Myopic subjects of both sex and various age groups underwent retinal nerve fiber layer thickness, macular volume in 6mm analysis by Rtvue Avanti SD-OCT, Optovue Technology V6.1.1,after taking due consent from ethical committee. Subjects were divided into two groups based on their refractive error, Group A <6 D and Group B >6D. The results were evaluated to determine the above mentioned measurements and their variation with myopic refractive error.

RESULTS

The RNFL thickness in four Quadrants and an inner circle were taken. The mean thickness in inner circle in both groups were 101.48μm (SD±13.34 μm) and 92.38 μm (SD±11.99μm) respectively, which was statistically significant. The difference was also significant in superior, nasal and inferior quadrant. Statistically the difference was not significant in temporal quadrant. The macular volume was calculated in 6mm diameter. The mean value in Group A was 7.82mm³±0.54 mm ³. The mean value in Group B was 7.44mm³±0.98mm³. The statistical analysis showed the difference between the two groups is statistically significant.

CONCLUSION

RNFL thickness is an established way to diagnose open angle glaucoma in preperimetric stage. Macular Volume is also found to be co-related with the risk. Myopes are known to be at higher risk to develop POAG. Hence, measurement of RNFL thickness by OCT should be made a mandatory investigation in High Myopes.

Evaluation of myopia on retinal nerve fiber layer thickness measured by Spectralis optical coherence tomography

The aim of the present study was to evaluate the retinal nerve fiber layer (RNFL) thickness of myopic subjects using Spectralis optical coherence tomography (OCT) and to determine variations with age and sex. A total of 271 Chinese participants with a spherical equivalent <+0.50 diopters were enrolled in the research. All subjects underwent a full ophthalmic examination. RNFL thickness was measured and compared according to sex, age and spherical equivalent. No significant difference was demonstrated between RNFL thickness in males and females. No significant difference was observed between RNFL thickness of the two age groups (≤12 years old and >12 years old). Significant differences were observed in all subfields of RNFL thickness among different spherical equivalent groups (P<0.05). In conclusion, myopia did have special influence on RNFL thickness, which was not related to sex or age.

Evaluation of Peripapillary Nerve Fiber Layer after Dexamethasone Implantation (Ozurdex) in Branch Retinal Vein Occlusions

Purpose. To evaluate the peripapillary retinal nerve fiber layer (RNFL) thicknesses of patients treated with intravitreal Ozurdex implant due to branch retinal vein occlusion (BRVO) related macular edema (ME). Methods. Thirty-three eyes of 33 patients treated with Ozurdex implant due to ME associated with BRVO were included in the study. Ophthalmic examinations including determination of best corrected visual acuity (BCVA), measurement of intraocular pressure (IOP), and central macular thickness (CMT) and peripapillary RNFL assessment with optical coherence tomography (OCT) were performed before the injection of Ozurdex implant and during the 6-month follow-up period after the injection. Results. The mean age was 55.2 ± 7.4 (range: 40-68) years. The BCVAs were significantly increased and CMTs were significantly decreased at month 3 and month 6 visits compared to baseline values. The mean IOP was significantly increased from baseline at day 1, week 1, and month 1 visits (p₁ = 0.008, p₂ = 0.018, and p₃ = 0.022, resp.). The average and inferior quadrant peripapillary RNFL thicknesses were significantly reduced at month 6 control visit compared to baseline values (both p < 0.001). Conclusions. Ozurdex implant improved the BCVA and reduced the CMT in the eyes with RVO related ME. However, IOP elevations occurred within the first month after the injection and the average and inferior quadrant RNFL thinning was found six months after the injection. Further controlled studies are warranted.

Optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy in retinal nerve fiber layer measurements of glaucoma patients

PURPOSE

To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO).

MATERIALS AND METHODOLOGY

114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems.

RESULTS

The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R²) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R² = 0.513) and between GDx VCC and GDx Pro (R² = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R² = 0.339 and Cirrus OCT R² = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R² = 0.207 and Cirrus OCT R² = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R² = 0.254, Cirrus OCT R² = 0.158, GDx Pro R² = 0.086 and GDx VCC R² = 0.1).

CONCLUSION

The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish between different retinal layers. This may explain the rather poor correlations and associations between CSLO measurements and those of all other imaging devices which makes it difficult to compare HRT 3 nerve fiber data. These correlations are important in clinical routine especially when different techniques are used in the follow-up of glaucoma patients.

Comparison of OCT measurements between high myopic and low myopic children

PURPOSE

To compare the peripapillary retinal nerve fiber layer (RNFL) thickness, macular thickness, and total macular volume of high myopic eyes with those of low myopic eyes in children younger than 10 years.

METHODS

Prospective, randomized, comparative study. Time-domain optical coherence tomography (OCT) (Stratus OCT; Carl Zeiss Meditec) was performed on 15 children with high myopia (refractive error greater than or equal to -6.0 diopters [D], group 1) and 20 children with low myopia (0 less than refractive error from -0.25 to -3.0 D, group 2). Fast RNFL scan and a fast macular scan with OCT were performed in both groups. The authors compared the data between the two groups.

RESULTS

The mean age of the patients with high myopia was 7.8 years and that of those with low myopia was 7.2 years. The mean overall thickness of the peripapillary RNFL was 100.8 μm in the high myopes and 110.5 μm in the low myopes. There was a statistically significant difference in the overall RNFL thickness between the two groups (p < 0.05). In addition, peripapillary RNFL thinning was especially prominent in the inferior quadrant in children with high myopia (p = 0.021). The mean values of macula thickness and volume for high myopes were also significantly smaller than the mean values for low myopes (p < 0.05).

CONCLUSIONS

The inferior quadrant and the overall peripapillary RNFL were significantly thinner in high myopic children relative to low myopic children. High myopic children had significantly thinner macular thickness and lower macular volumes. These structural differences should be considered in the clinical assessment of high myopic children.

Evaluation of peripapillary retinal nerve fiber layer thickness in patients with vitamin B12 deficiency using spectral domain optical coherence tomography

PURPOSE

To compare peripapillary retinal nerve fiber layer (RNFL) thicknesses measured by Cirrus HD optical coherence tomography (OCT) of patients with vitamin B12 deficiency with healthy controls and to evaluate the correlation between the peripapillary RNFL thickness and plasma vitamin B12 levels.

MATERIALS AND METHODS

Forty-five patients (19 male and 26 female) with a diagnosis of vitamin B12 deficiency (patient group) and 45 age- and sex- matched healthy subjects (control group) were consecutively enrolled in this study. Average, temporal, nasal, inferior, and superior quadrant peripapillary RNFL thicknesses of each subject were obtained using the Cirrus HD OCT. Disc area (DA) and rim area (RA), central subfield thickness (CST), cube volume (CV), and cube average thickness (CAT) were also measured.

RESULTS

Mean age of each group was 33.1 ± 6.5 years (range: 21-45 years). Mean plasma vitamin B12 level was 114.8 ± 34.0 pg/mL in the patient group and was 405.1 ± 20.0 pg/mL in the control group (p < 0.001). The patient and control groups were similar regarding axial length, plasma folate levels, DA, RA, CST, CV, CAT, and RNFL thicknesses in superior, nasal, and inferior quadrants. However, average RNFL and RNFL in temporal quadrant were significantly thinner in the patient group than in the control group (p = 0.013 and p < 0.001, respectively). In addition, temporal (r = 0.356, p = 0.001) and average (r = 0.212, p = 0.045) peripapillary RNFL thicknesses were correlated with plasma vitamin B12 levels.

CONCLUSION

We have shown that, as in other non-glaucomatous optic neuropathies, temporal quadrant RNFL thickness was thinner in patients with vitamin B12 deficiency and it was correlated with plasma vitamin B12 levels. Further studies are warranted to clarify the clinical relevance of these findings and the effects of vitamin B12 replacement therapy.

Influence of refractive error on optic disc topographic parameters: the singapore malay eye study

PURPOSE

To examine the relationship between refractive error and optic disc topographic parameters and retinal nerve fiber layer (RNFL) thickness.

DESIGN

Population-based cross-sectional study.

METHODS

All 3,280 (78.7% response rate) persons of Asian Malay ethnicity 40 to 80 years of age underwent a standardized interview, ocular examinations, and optic disc imaging with the Heidelberg Retina Tomography II (HRT; Heidelberg Engineering). Associations between spherical equivalent (SE) and HRT parameters were evaluated by partial correlation analysis.

RESULTS

There were 2,457 (74.9%) right eyes with good-quality HRT images for analyses. When compared with emmetropic eyes, highly myopic eyes (SE < -6.0 diopters) had greater disc area, rim area, rim volume, whereas hyperopic eyes (SE > 0.5 diopters) had significantly smaller disc area, rim area, and cross-sectional RNFL area (all P < .005). In partial correlation after adjustment for age, sex, body mass index, intraocular pressure, and optic disc area, increase of SE (toward hyperopia) was related significantly with greater cup area (partial correlation coefficient, r = 0.058; P = .004) and cup-to-disc area ratio (r = 0.058; P = .004) and with smaller optic disc area (r = -0.058; P = .004), rim area (r = 0.058; P = .004), and rim volume (r = -0.091; P < .001).

CONCLUSIONS

This population-based study shows that refractive error is significantly (but weakly) associated with HRT parameters of disc area, cup area, rim area, cup-to-disc area ratio, and rim volume. The clinical significance of these associations need to be determined in further studies.

Assessment of optic disc parameters among healthy adult Malays by Heidelberg Retinal Tomograph II

BACKGROUND

This study aims to assess the optic disc characteristics in healthy adult Malays and to correlate them with age, gender and refractive errors.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 200 voluntary participants (106 women and 94 men) among Malay students aged 20 to 37 years at Health Campus, Universiti Sains Malaysia.

METHODS

The relationship between Heidelberg Retinal Tomograph parameters with age, gender and refractive error were analysed with correlation tests and multiple linear regression analyses.

MAIN OUTCOME MEASURES

  Twelve parameters, that is, disc area, rim area, cup area, cup to disc area, cup volume, rim volume, height variation contour, cup shape measure, mean cup depth, maximum cup depth, mean retinal nerve fibre layer thickness and retinal nerve fibre layer cross-sectional area.

RESULTS

  Disc area, rim area and cup : disc area ratio averaged 2.24 ± 0.52 (mean ± standard deviation), 1.64 ± 0.32 and 0.25 ± 0.12 mm(2) , respectively. Five parameters (disc area, cup area, cup volume, cup : disc area ratio and mean retinal nerve fibre layer thickness) showed statistically significant difference between men and women. Age was negatively and significantly correlated with rim area with coefficient r = -0.21, P = 0.003. All optic disc parameters were significantly correlated (P < 0.05) with disc area, except cup shape measure.

CONCLUSIONS

  One or more of optic disc parameters were affected significantly by age, gender and disc area in healthy adult Malays' eyes. These factors need to be considered during the evaluation of optic disc.

Normative database of retinal nerve fiber layer and macular retinal thickness in a Thai population

PURPOSE

To investigate the distribution of retinal nerve fiber layer (RNFL) and macular retinal thickness measured by optical coherence tomography (OCT) in a Thai population.

METHODS

We studied one eye each of 250 healthy subjects [age > or = 18 years; spherical refractive error within +/-6 diopters (D); astigmatism < or =3 D; no ocular pathology]. A complete eye examination, standard automated perimetry, and fast RNFL and macular thickness measurement by OCT were performed, and a disc photograph was taken. The distributions of both thicknesses, including their relationship with demographic data, were analyzed.

RESULTS

The mean +/- SD age of the study population was 44.7 +/- 12.2 years. The mean +/- SD RNFL thickness was 109.3 +/- 10.5 m, which was 10% thicker than that in the OCT normative database. RNFL decreased 2.3 m per decade (P < 0.001). Sex and spherical equivalent were not associated with RNFL thinning. The mean +/- SD central foveal thickness was 183.2 +/- 1.3 m. The macular thickness in the outer area was significantly thinner than that in the inner area (P < 0.001). The temporal regions were the thinnest among the four quadrants (P < 0.001). Thinning of all macular areas, except the center, was found to be associated with advancing age (P < 0.05).

CONCLUSIONS

RNFL thickness in the measured Thai population was about 10% thicker than that in the original normative database. Macular thickness and RNFL thickness in the superior and inferior quadrants decreased with advancing age.

Scanning laser polarimetry with variable corneal compensation in primary angle-closure glaucoma

PURPOSE

To evaluate the diagnostic sensitivity of scanning laser polarimetry in primary angle-closure glaucoma (PACG) as compared with that in primary open-angle glaucoma (POAG) and to compare the retinal nerve fiber layer (RNFL) distribution between PACG and POAG.

DESIGN

Prospective, comparative, observational cases series.

PARTICIPANTS

One eye each of 58 PACG patients and 51 POAG patients.

METHODS

Scanning laser polarimetry with variable corneal compensation (GDx VCC).

MAIN OUTCOME MEASURES

GDx VCC temporal-superior-nasal-inferior-temporal (TSNIT) parameters, including TSNIT average, TSNIT standard deviation, superior average, and inferior average, as well as the nerve fiber indicator (NFI).

RESULTS

By using a logistic marginal regression model that defined an abnormal test as P<5% for each of the TSNIT parameters or NFI > or = 31, we found that diagnostic sensitivities of the GDx VCC parameters were similar (all Ps>0.05) in PACG and POAG despite the differences in refraction error (P = 0.017), axial length (P<0.001), and disc diameters (vertical, P = 0.031; horizontal, P = 0.002) between these 2 forms of glaucoma. The between-group similarity in the diagnostic sensitivity remained true either when all eyes were considered together or in each severity group, based on the visual field scoring system adopted by the Advanced Glaucoma Intervention Study. Regarding the RNFL distribution, the parameter inferior average was greater than the superior average in either PACG (P = 0.010) or POAG (P = 0.006). Further subgroup analyses found significant superior-inferior asymmetry in mild PACG (P = 0.022) but not in mild POAG (P = 0.279).

CONCLUSIONS

Eyes with PACG have ocular biometrics and, possibly, pathogeneses of optic nerve damage different from those of eyes with POAG; however, the diagnostic sensitivity of GDx VCC is quite comparable in these 2 forms of glaucoma, irrespective of disease severity.

The influence of low to moderate myopia on retinal nerve fiber layer as assessed by scanning laser polarimetry with variable corneal compensator

PURPOSE

To evaluate the influence of different degrees of myopia on retinal nerve fiber layer (RNFL) as measured by scanning laser polarimetry (SLP) with variable corneal compensator (VCC) in healthy eyes.

METHODS

One hundred and seventy-four healthy age-matched subjects with low to high myopic and emmetropic eyes underwent RNFL measurement by means of GDxVCC. The GDx parameters included in the analysis were: Temporal-superior-nasal-inferior thickness (TSNIT) average, Superior average, Inferior average, TSNIT standard deviation, Inter-eye symmetry, NFI, Symmetry, Superior ratio, Inferior ratio, Superior/nasal, Maximum modulation, Superior maximum, Inferior maximum, Ellipse modulation, Normalized superior area, Normalized inferior area, Ellipse standard deviation, Ellipse average. The mean value of each SLP parameter of myopic eyes was compared with the mean value of the same parameter of emmetropic eyes.

RESULTS

Mean myopia was 3.9 +/- 1.5 dpt (range: -2 to -8.25 dpt). TNSIT average was higher in myopic group (p = 0.0111), together with Superior average (p = 0.0244), Symmetry (p < 0.0001) and Ellipse average (p = 0.0111). Two ratio parameters, Superior ratio and Inferior ratio, were higher in emmetropic eyes (p = 0.0179 in both cases). In both the myopic and the emmetropic group, all the SLP assessments of the RNFL fell within the normal range, according to the GDx database.

CONCLUSIONS

Low to high myopia is not related to clinically relevant variations of SLP parameters, as assessed with GDx-VCC.

Optic Disc Topography and Peripapillary Retinal Nerve Fiber Layer Thickness in Nonarteritic Ischemic Optic Neuropathy and Open-Angle Glaucoma

OBJECTIVE

To evaluate the results of scanning laser tomography and scanning laser polarimetry (SLP) and the correlations with visual field damage (VFD) in eyes with nonarteritic ischemic optic neuropathy (n-AION) compared with eyes with open-angle glaucoma (OAG).

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirty-three eyes of 33 patients with n-AION and 33 eyes with OAG whose age and VFD evaluated with the Humphrey field analyzer were matched to those of the n-AION eyes.

MAIN OUTCOME MEASURES

The parameters of optic disc topography obtained with the Heidelberg Retina Tomograph II (HRT II) and retinal nerve fiber layer (RNFL) thickness with GDx with variable corneal compensation and the correlation to VFD.

RESULTS

The cup area, cup-to-disc area ratio, and mean cup depth were significantly smaller, and the cup shape measure more negative, in the n-AION eyes than in the OAG eyes (P<0.001), whereas rim area was significantly greater (P<0.001). Multivariate analyses showed that none of disc area, rim area, and mean cup depth in the n-AION eyes and only rim area (P = 0.029) in the OAG eyes was significantly associated with mean deviation (MD). Ellipse average of RNFL thickness significantly correlated with MD in the n-AION eyes (P = 0.045) and in the OAG eyes (P = 0.022).

CONCLUSIONS

Disc topography of eyes with n-AION was quantitatively characterized by small and shallow cupping and a relatively large rim area compared to eyes with OAG matched for age and VFD. In eyes with n-AION, significant correlation with VFD was found only for the RNFL thickness evaluated with SLP but not for the HRT II parameters.