Investigating mechanisms of myopia in mice

Genetic and environmental factors have been shown to control visually-guided eye growth and influence myopia development. However, investigations into the intersection of these two factors in controlling refractive development have been limited by the lack of a genetically modifiable animal model. Technological advances have now made it possible to assess refractive state and ocular biometry in the small mouse eye and therefore to exploit the many genetic mouse mutants to investigate mechanisms of visually-guided eye growth. This review considers the benefits and challenges of studying refractive development in mice, compares the results of refractive error and ocular biometry from wild-type strains and genetic models in normal laboratory visual environments or with disrupted visual input, and discusses some of the remaining challenges in interpreting data from the mouse to validate and standardize methods between labs.

Macular hole surgery in a patient who cannot maintain facedown positioning

Aim

To present macular hole surgery in a patient who had previously undergone thyroid removal surgery.

Material and Methods

During thyroid gland removal surgery, the recurrent laryngeal nerves were cut by the surgeon. Therefore, the patient had to have a tracheotomy and because of this unusual situation, the patient could not breathe if lying ‘upside-down’. Complete ophthalmic examination and spectral optical coherence tomography was performed in a 77-year-old woman before and after macular hole surgery.

Results

The patient was treated by the ‘inverted internal limiting membrane (ILM) flap technique’ with air tamponade for macular hole closure. This technique was described to have very high success rates in large, stage IV macular holes. Postoperatively, lying on her opposite side was advised. However, the macular hole remained open after this approach. Because of this, another approach was undertaken. The ILM flap technique and silicone oil were applied, and the patient was positioned on her opposite side. Silicone oil was removed after 3 months. Eighteen months later, the macular hole remained closed. Visual acuity improved from 10/200 to 20/50.

Conclusion

This case demonstrates that in an extremely select group of patients, silicone oil combined with the inverted flap technique may be considered for treatment of macular hole.

Correlation of spectral domain optical coherence tomography findings in acute central serous chorioretinopathy with visual acuity

Purpose

To evaluate the structural changes in the acute phase of central serous chorioretinopathy and after its resolution, using spectral domain optical coherence tomography, to correlate these tomographic changes with visual acuity (VA).

Method

This was a prospective study of 100 consecutive patients with acute central serous chorioretinopathy. It was based on presenting the best-corrected VA, divided into three groups (Group 1, n = 36, VA 6/6; Group 2, n = 49, VA 6/9–6/18; Group 3, n = 15, VA > 6/18). All patients underwent fundus evaluation followed by fluorescein angiography and spectral domain optical coherence tomography.

Results

The mean age of the patients was 40 ± 7.17 years. The mean log MAR VA was 0.176 ± 0.0185. Single pigment epithelial detachment (PED), and multiple discrete and multiple confluent PEDs were seen in 21%, 17%, and 32% of the eyes, respectively. The location of the PED was subfoveal in 35% of the eyes. The presence of subretinal fibrin and a rough undersurface of the neurosensory retina were noted in 61% and 64% of the eyes, respectively. On en-face scanning, a break in the walls of the PED and overlying fibrin were seen in 32.8% and 45% of the eyes, respectively. The mean subretinal fluid height at the fovea was 279.11 ± 148.78 μ. The mean outer nuclear layer thickness during the active stage was 95.10 μ and during the resolved stage, it was 77.69 μ (P = 0.012). The average photoreceptor lengths were 73.1 μ, 84.6 μ, and 94.9 μ in groups 1, 2, and 3, respectively, in the acute phase; and 69.5 μ, 70.8 μ, and 61.6 μ, respectively, after resolution (P = 0.013, P = 0.010, and P = 0.011).

Conclusion

In the acute phase of the disease, poorer VA showed statistically significant association with greater dimensions of subretinal fluid – particularly, greater subretinal fluid height and thinning of the outer nuclear layer at the fovea. The presence of fibrin, subretinal precipitates, subfoveal location, or type of PED did not have any association with poor VA. In resolved central serous chorioretinopathy, poorer VA was associated with a persistently thinner outer nuclear layer, shorter photoreceptor lengths, and inner and outer segment junction atrophy.

Two cases of X-linked retinoschisis with different spectral domain optical coherence tomography findings

Spectral domain optical coherence tomography was used to image the maculae of two brothers who had the diagnosis of X-linked retinoschisis maculopathy. One patient demonstrated a large foveal cyst in one eye and a lamellar macular hole in the fellow eye. The second patient demonstrated small retinal cysts in multiple layers of the retina. Spectral domain optical coherence tomography allowed high-resolution imaging and characterization of the features in X-linked retinoschisis in these patients, and it highlighted the variability of the same genetic disease, even in one family.

The use of SD-OCT in the differential diagnosis of dots, spots and other white retinal lesions

PURPOSE

To demonstrate the utility of a retinal imaging technique using spectral domain optical coherence tomography (SD-OCT) for creating a B-scan layer-by-layer analysis to aid in the differential diagnosis of various retinal dots, spots, and other white lesions.

DESIGN

Review.

METHODS

A retrospective review of imaging studies performed with SD-OCT (Topcon, 3DOCT-2000, Oakland, NJ) at SUNY State College of Optometry.

RESULTS

B-scan layer-by-layer analysis and unique SD-OCT reflectivity patterns of the following retinal white lesions are reviewed in the order of their retinal layer localization: myelinated nerve fiber layer, cotton wool spot, exudates, edema residues, drusen, fundus albipunctatus, Stargardt disease, Bietti crystalline dystrophy, punctate inner choroidopathy (PIC), presumed ocular histoplasmosis syndrome (POHS), post-photocoagulation chorioretinal scarring, and osseous choristoma.

CONCLUSION

The reviewed images demonstrate the utility of SD-OCT in the identification of the unique characteristics of the presented retinal pathologies. SD-OCT is ideal for retinal layer localization of lesions, thus enhancing the differential diagnosis of retinal dots, spots, and other white lesions. Even though true pathognomonic patterns are rare, highly suggestive findings of certain retinal abnormalities often facilitate immediate recognition and diagnosis.

Isolated cotton-wool spots of unknown etiology: management and sequential spectral domain optical coherence tomography documentation

Cotton-wool spots (CWSs) are common retinal manifestations of many diseases including diabetes mellitus, systemic hypertension, and acquired immunodeficiency syndrome. Clinically they appear as whitish, fluffy patches on the retina and eventually fade with time. In this study, spectral domain optical coherence tomography (SD-OCT) with mapping was used to demonstrate in vivo the characteristics of an isolated CWS in a 59-year-old patient as well as its appearance immediately after ophthalmoscopic resolution. Presented here is the work-up and management of this clinical problem for the ophthalmologist. The authors propose that SD-OCT could be a valuable research tool in characterizing and following the dynamic CWS changes at individual retinal layer level, with potential clinical applications as a screening or diagnostic tool in CWS-related diseases.

A case of acute retinal pigment epithelitis: spectral domain optical coherence tomography time course and physiopathologic hypothesis

Purpose:

To report the time course of retinal morphologic changes in a patient with acute retinal pigment epithelitis (ARPE) using spectral domain optical coherence tomography (SD-OCT).

Methods:

A 30-year old man was referred for blurred vision of his right eye after five days that appeared suddenly 15 days after recovery from a flu-like syndrome. SD-OCT was performed immediately, followed by fluorescein and infracyanine angiography at eight days and then at three weeks.

Results:

At presentation, a bubble of sub-macular deposit was observed on the right macula with central golden micronodules in a honeycomb pattern. SD-OCT showed an “anterior dislocation” of all the retinal layers up to the inner/outer segment (IS/OS) line and irregular deposits at the OS level together with thickening of the retinal pigment epithelial (RPE) layer. As visual acuity increased, eight days later, the OCT showed reduction of the sub-retinal deposits and an abnormal hyperflectivity of the sub-retinal and RPE layers was observed. The patient showed a positive serology for picornavirus.

Discussion:

The acute SD-OCT sections of this patient with ARPE were compared with histological sections of a 35 day old Royal College of Surgeons rat. Similar findings could be observed, with preservation of the IS/OS line and accumulation of debris at the OS level, suggesting that ARPE symptoms could result from a transient phagocytic dysfunction of the RPE at the fovea, inducing reversible accumulation of undigested OS. Picornaviruses comprising enterovirus and coxsachievirus described as being associated with acute chorioretinitis. In this case, it was responsible for ARPE.

Conclusion:

We hypothesize that ARPE syndrome results from a transient dysfunction of RPE, which can occur as a post viral reaction.

Sequential spectral domain OCT documentation of retinal changes after branch retinal artery occlusion

Branch retinal artery occlusions (BRAO) are characterized histopathologically by inner retinal edema initially and atrophy in the presence of persistent ischemia. The duration of ischemia leading to irreversible atrophic retinal changes is not clear. Spectral-domain optical coherence tomography (SD-OCT) provides non-invasive detailed in-vivo histological changes in the retina. In this case report, we show sequential in vivo pathological changes seen in the inner retinal layers, in spite of clinical improvement, following the migration of an intraretinal embolus on the optic nerve head, which had previously resulted in symptomatic BRAO.

Spectral Domain OCT Documented Resolution of Pseudophakic Cystoid Macular Edema after Intravitreal Triamcinolone

Cystoid macular edema (CME) is an important cause of visual loss after cataract surgery. Treatment is usually with topical anti-inflammatory agents, with anti-vascular endothelial growth factor agents and steroids used intravitreally in resistant cases. Even though time-domain Stratus OCT can quantify the macular thickness, it cannot prognosticate visual outcomes due to the poor resolution of images, especially the outer segment-inner segment junction. Spectral-domain OCT (SD-OCT) by its ability to acquire large number of images in a short span of time provides high resolution cross-sectional images of the retina, which not only highlights the underlying pathological changes, but in addition can prognosticate visual recovery. We describe pre and post SD-OCT features of a case of refractory CME who was treated with intravitreal triamcinolone actetonide.

Spectral domain optical coherence tomographic findings at convalescent stage of acute zonal occult outer retinopathy

Purpose

To describe the morphology of the retina at the convalescent stage of acute zonal occult outer retinopathy (AZOOR) from images obtained by spectral domain optical coherence tomography (SD-OCT).

Methods

The visual fields, electroretinograms (ERGs), and OCT images were reviewed in two women aged 24 and 33 years. The patients were followed for one and four years, respectively.

Results

In both cases, the anterior and posterior segments were almost normal, although both patients had a sudden unilateral vision decrease and photopsia. Goldmann perimetry revealed enlarged blind spots and scotomas. The ERGs were reduced in both cases. SD-OCT showed that the junction of the inner and outer segment, the IS/OS line, of the photoreceptors was irregular or lost in the affected retinas. The retina in these areas was thinner due to a decrease in the thickness of both the outer nuclear layer (ONL) and inner nuclear layer (INL) in Case 2.

Conclusions

The decrease in retinal thickness at the convalescent stage of AZOOR is most likely due to a shortening of not only the photoreceptors and ONL but also to a thinning of the INL in a severe case.