Accurate Cross-Section Estimation of Blood Vessels in Choroidal Haller's Layer: An Iterative Method based on 3D Tensor Voting

Various eye diseases, including polypoidal choroidal vasculopathy (PCV) and age-related macular degeneration (AMD), affect choroidal vasculature early, but possibly minutely. However, due to the complex networked structure of the vasculature, it becomes hard to visualize, analyze and detect such changes in 2D OCT B-scan images. In contrast, algorithmic evaluation of cross-section facilitates clinicians in tracing minute variations in the vessel network, and quantifying those correlated with pathologies, potentially leading to early diagnosis. In this context, we proposed a novel method of estimating vessel cross-sections in choroidal Haller's layer. Accuracy of our method was evaluated on synthetic as well as clinical data by trained optometrists, and earned a confidence score of 90%, marking about 60% improvement over estimates based on a well-known tree-based method.

Correlation between retinal sensitivity and cystoid space characteristics in diabetic macular edema

PURPOSE

To evaluate the correlation between retinal sensitivity and cystoid space characteristics in eyes with diabetic macular edema (DME).

MATERIALS AND METHODS

Prospective cross-sectional study of 22 subjects with DME (32 treatment-naïve eyes). All study subjects underwent complete ophthalmic examination, including slit-lamp biomicroscopy and dilated fundus examination. All subjects underwent spectral domain optical coherence tomography (SD-OCT) and microperimetry (MP). Intraretinal cystoid space (ICS) volume was generated after manual delineation of cystoid space boundaries using the three-dimensional-OCT software. Various SD-OCT parameters, including retinal thickness, retinal volume, cystoid space volume, cystoid space intensity, and outer retinal structure integrity, were correlated with MP parameters and best-corrected visual acuity (BCVA).

RESULTS

Subject's mean age was 57 ± 9 years. The mean logarithm of minimum angle of resolution BCVA was 0.4 ± 0.2. The intraclass correlation coefficient for inter- and intra-grader assessment of cystoid space volume by manual delineation was 0.99 and 0.99, respectively. Mean total ICS volume was 0.4 ± 0.4 mm 3 and for the foveal center, subfield was 0.1 ± 0.1 mm 3 . Mean retinal sensitivity was 12.89 ± 10 dB; however, foveal retinal sensitivity was 12.3 ± 11.1 dB. We found no significant correlation between BCVA and total cystoid space volume (r = 0.33, P = 0.06). Correlation between total retinal sensitivity and total ICS was negative and nonsignificant (r = -0.17, P = 0.36). Correlation between foveal retinal sensitivity and foveal cystoid space intensity was moderate and marginally significant (r = -0.43, P = 0.05).

CONCLUSION

Total cystoid space volume was not significantly correlated with BCVA or total retinal sensitivity in subjects with DME. Foveal cystoid space optical intensity was negatively correlated with foveal retinal sensitivity. These findings suggest further investigation of cystoid space characteristics in the setting of DME may be of value.

Choroidal thickness in diabetic patients of Indian ethnicity

Purpose:

To evaluate choroidal thickness (CT) change in various grades of diabetic retinopathy (DR) in comparison to age-matched healthy subjects.

Methods:

This prospective observational study included 227 eyes of 125 subjects with diabetes (study group: 58 females) and 197 eyes of 110 age-matched healthy subjects (control group: 66 females). Collected data included age, gender, duration of diabetes, glycemic control, comprehensive ocular examination, fundus photography, and CT measurement on spectral domain ocular coherence tomography using enhanced depth imaging.

Results:

Mean age in the study group was 57.0 ± 9.37 years (43–73 years). The mean age was 41.48 ± 5.43 years in the control group. Subjects with diabetes with (252.8 ± 55.6 microns) and without (261.71 ± 51.8 microns) retinopathy had significantly thinner choroids when compared to the control group (281.7 ± 47.7 microns; P = 0.032). Seventy-four of 227 eyes did not have any evidence of DR, 89 eyes had features of nonproliferative diabetic retinopathy (NPDR), and 33 eyes had treatment naïve proliferative diabetic retinopathy (PDR). Thirty-one PDR eyes had received previous laser photocoagulation. Subjects with diabetes without retinopathy had a greater subfoveal choroidal thickness (SFCT) than subjects with diabetes with retinopathy (P < 0.001). Eyes with PDR (243.9 ± 56.2 microns) had thinner SFCT than those with NPDR (238.98 ± 111.23 microns). There was no difference in the SFCT between treated (laser photocoagulation done; 251.784 ± 103.72 microns) and treatment naïve PDR (258.405 ± 89.47 microns, P = 0.23).

Conclusions:

Control eyes had greater SFCT compared to subjects with diabetes, with and without retinopathy. The thinning progressed with increasing severity of DR. Choroidal thinning may contribute to DR pathogenesis.

Choroidal thickness profile in healthy Indian children

Purpose:

The purpose was to study choroidal thickness and its profile based on location in healthy Indian children using enhanced depth spectral-domain-optical coherence tomography (SD-OCT).

Methods:

In this cross-sectional observational study 255 eyes of 136 children with no retinal or choroidal disease were consecutively scanned using enhanced depth SD-OCT. Eyes with any ocular disease or axial length (AXL) >25 mm or < 20 mm were excluded. A single observer measured choroidal thickness from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-microns intervals up to 2500 microns temporal and nasal to the fovea. Generalized estimating equations were used to evaluate the correlation between choroidal thickness at various locations and age, AXL, gender and spherical equivalent (SEq).

Results:

Mean age of the subjects was 11.9 ± 3.4 years (range: 5–18 years). There were 62 Females and 74 males. The mean AXL was 23.55 ± 0.74 mm. Mean subfoveal choroidal thickness was 312.1 ± 45.40 μm. Choroid was found to be thickest subfoveally, then temporally. Age, AXL and SEq showed a significant correlation with choroidal thickness, whereas gender did not affect choroidal thickness.

Conclusion:

Our study provides a valid normative database of choroidal thickness in healthy Indian children. This database could be useful for further studies evaluating choroidal changes in various chorioretinal disorders. Age and AXL are critical factors, which negatively correlated with choroidal thickness.

Retrospective hospital-based analysis of age-related macular degeneration patterns in India: 5-year follow-up

PURPOSE

To provide a detailed analysis of age-related macular degeneration (AMD) with a 5-year follow-up at a Tertiary Eye Care Center in India.

METHODS

In this retrospective institutional study, 408 eyes of 204 subjects (100 males) with a diagnosis of AMD with minimum 5-year follow-up were included. Data collected included demographics, details of the ocular exam, special investigations performed, treatment offered, complications, and systemic diseases, if any.

RESULTS

The median age was 74.24 ± 8.23 years. Median follow-up was 5.77 years. The visual acuity (VA) at baseline and last visit was 0.74 ± 0.12 (Snellen's equivalent 20/100) and 0.54 ± 0.12 logarithm of the minimum angle of resolution (Snellen's equivalent 20/50; P = 0.032) in patients with choroidal neovascular membrane (CNVM). The most common complaint was decreased vision (94.5%). AMD (any stage) was found to be bilateral in 93% of patients at baseline and 197 patients (96.56%) at 5 years. Seventeen eyes had active CNVM (12 of these were occult) at presentation. At baseline, 43 eyes had a disciform scar. Three hundred twenty-one eyes had dry AMD at baseline (geographic atrophy - 12 [3.7%] eyes). Five-year conversion rate into wet AMD and geographic atrophy was 2.87% and 3.12%. Median number of anti-vascular endothelial growth factor injections administered per patient was 2.8 ± 1.2. CNVM bilaterality was low (7.5%).

CONCLUSION

Patients with AMD in India presented later in the course of the disease. Bilateral advanced AMD and geographic atrophy were uncommon. Five-year conversion rate into wet AMD and geographic atrophy was 2.87% and 3.12%.

Vitreous haemorrhage in massive hemorrhagic polypoidal choroidal vasculopathy: clinical characteristics and surgical outcomes: Vitreous hemorrhage in PCV

Background

To report the outcomes of vitreous hemorrhage (VH) associated with hemorrhagic polypoidal choroidal vasculopathy (PCV).

Methods

A retrospective study of 28 eyes of 27 consecutive patients of hemorrhagic PCV with VH, which were managed surgically between January 2003 and December 2011, was performed. All patients underwent pars plana vitrectomy for VH associated with PCV. The main outcome measure was best-corrected visual acuity (BCVA) at baseline, at 1, 3 and 6 months post operatively and at last follow up.

Results

The visual acuity measured on early treatment diabetic retinopathy study (ETDRS) chart improved in 16 eyes (57.1 %) by two or more lines, remained unchanged in nine eyes (32.1 %) and decreased in three (10.7 %) after surgery when compared to baseline VA. The mean baseline VA was 2.69 ± 0.57 logMAR units (<20/2000) which improved to 1.65 ± 0.93 logMAR units (20/800) at 1 month post operative visit and was sustained at 1.72 ± 1.12 (20/800) with an improvement of 0.96 logMAR units (p < 0.001, 95 % CI 0.54–1.37). The average postoperative follow up was for 14.2 months (range 1–84). The complications noted in postoperative follow up were cataract (n = 10), macular scaring (n = 9), organised dehemoglobinised blood (n = 7), retinal tear or detachment (n = 5), recurrent VH (n = 3) and choroidal detachment (n = 1).

Conclusion

Majority of patients with loss of vision due to VH secondary to hemorrhagic PCV have sustained improvement in visual acuity following surgery.

Vitreo-retinal interface changes on optical coherence tomography in the fellow eyes of patients with macular hole

AIM

To study the vitreo-retinal interface and macular changes on optical coherence tomography (OCT) in the fellow eyes of patients with macular hole.

METHODS

Patients with idiopathic macular hole in one or both eyes presented to our institute between January 2003 and December 2009 were evaluated retrospectively. Demographic details, best-corrected visual acuity and vitreo-retinal interface, and macular changes of the fellow eye on OCT were studied.

RESULTS

Seventy patients underwent OCT of both eyes during the study period. The average age group was 61.96 years and 35 (50%) were females. Among the fellow eyes, normal foveal contour was noted in 36 (51.4%) eyes and 34 (48.6%) eyes were observed to have vitreo-retinal interface changes. Of them, 13 (18.6%) eyes had some stage of full thickness macular hole and 21 (30.0%) eyes had interface changes. There was no statistical correlation between involved eye lesions (P=0.64) or visual acuity (P=0.55) as predictors of development of either fellow eye lesions or poor visual acuity.

CONCLUSION

There is a significant chance of having vitreo-retinal interface findings in the fellow eyes of patients presenting with macular hole. OCT should be considered in both eyes of patients with macular hole to detect early changes in the fellow eyes, which may require an early intervention.

Hypopyon uveitis following panretinal photocoagulation in a diabetic patient

We report the case of a 42-year-old man with uncontrolled diabetes mellitus who presented to us with diminution of vision in both eyes for the past two years. On examination, both eyes showed features of high-risk proliferative diabetic retinopathy and the patient was advised of panretinal photocoagulation (PRP). He underwent the first sitting of PRP in both eyes. On the following day, he developed hypopyon uveitis in the right eye. He was treated with topical steroid and cycloplegic, and complete resolution of hypopyon was achieved over the next three days. This case highlights the importance of adequately controlled diabetes mellitus before PRP. Hypopyon uveitis could be a complication of PRP in patients with uncontrolled diabetes mellitus who respond to frequent topical steroid and cycloplegic.

Panuveitis as a manifestation of ocular syphilis leading to HIV diagnosis

Syphilis is a rare cause of panuveitis. We present the case of a 33-year-old man who presented with diminution of vision of three months duration in his left eye (OS), without any other systemic illness. Ophthalmic examination showed features of pauveitis with dense vitreous exudates, disc pallor and sheathing of vessels on fundoscopy. A diagnosis of probable endogenous endophthalmitis was made and vitreous tap performed. Vitreous biopsy showed no growth of fungus or bacteria. Rapid plasma reagin (RPR) and Treponema pallidum hemagglutination (TPHA) test were positive. Enzyme-Linked Immuno Sorbent Assay (ELISA) and Western Blot test were then performed, which revealed concurrent HIV infection. The patient improved dramatically with intravenous penicillin therapy. HIV positive patients may present with panuveitis secondary to ocular syphilis, as the only presenting feature in HIV positive patient in absence of any other systemic features.