Reply: 'Myopic foveoschisis: An ectatic retinopathy, not a schisis'

Full text: We thank Tsilimbaris et al1 for their comments on the appropriateness of the term ‘myopic foveoschisis’ to describe the condition that is characterized by the separation of neural retina layers associated with high myopia and posterior staphyloma. They have proposed the term ‘myopic ectatic retinopathy’ as a more literal and functionally more accurate descriptor of the condition to avoid the use of the word ‘schisis’, which may be misleading because it is also used to describe other conditions where there is separation of neural retina layers without the presence of staphyloma.2 Using the word ‘ectatic’ for this condition would imply that we are fairly certain about the pathogenesis and mechanistic factors that underlie its development and progression. However, this is not the case, unfortunately, as our review of the literature has shown. There are several theories ranging from vitreous traction to sclerosing changes of retinal vessels to progression of staphylomas as possible etiological factors. Therefore, it is likely to be multifactorial in nature—hence the success reported with different procedures that address either the vitreous traction factor using vitrectomy, peel plus tamponade or the scleral ectasia factor using posterior buckling techniques. In the absence of a good understanding of underlying pathogenesis, it is probably best to use purely descriptive names rather than mechanistic terms. The use of descriptive terms, even though similar, do not necessarily cause confusion as long as they are widely accepted as differentiating terminology, for example, postoperative pseudophakic cystoid macular edema (Irvine–Gass syndrome) vs cystoid macular edema associated with posterior uveitis in a phakic patient. The introduction of too many mechanistic or pathogenetic terms in the absence of clear understating of etiology can in fact cause more confusion, for example, serous chorioretinopathy vs central serous retinopathy vs serous choroidopathy. The confinement to broad descriptive terms can enhance communication and reduce confusion without committing to any presumption about etiology until it is better understood. This approach is probably best illustrated by the recent advances in the understanding of mactel21, a condition initially described and classified, using descriptive nomenclature, by Don Gass as bilateral, idiopathic acquired juxtafoveolar telangiectasis (Group2A) and as distinctly different from unilateral, congenital parafoveolar telangiectasis (Group 1A; Gass,3 pp 504–506 vs 127–128). Finally, it is worthy to note that for myopic foveoschisis associated with a staphyloma that is associated with outer layer macular detachment, Don Gass also descriptively included the additional observation (before the advent of OCT) that the retinal profile was concave rather than convex in shape, thereby differentiating it from rhegmatogenous detachments with recruitment of subretinal fluid that is associated with posteriorly located breaks and macular holes in myopic eyes. References 1.Tsilimbaris MK, Vavvas DG, Bechrakis NE. Myopic foveoschisis: an ectatic retinopathy, not aschisis. Eye 2016; 30: 328–329. 2.Powner MB, Gillies MC, Tretiach M, Scott A, Guymer RH, Hageman GS et al. Perifoveal müller cell depletion in a case of macular telangiectasia type 2. Ophthalmology 2010; 117(12): 2407–2416. 3.Gass DM. Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment, 4th edn. Mosby-Yearbook: St. Louis, 1997.

Initiation and progression of ossification of the posterior longitudinal ligament of the cervical spine in the hereditary spinal hyperostotic mouse (twy/twy)

Ossification of the posterior longitudinal ligament (OPLL) is a significantly critical pathology that can eventually cause serious myelopathy. Ossification commences in the vertebral posterior longitudinal ligaments, and intensifies and spreads with the progression of the disease, resulting in osseous projections and compression of the spinal cord. However, the paucity of histological studies the underlying mechanisms of calcification and ossification processes remain obscure. The pathological process could be simulated in the ossifying process of the ligament in mutant spinal hyperostotic mouse (twy/twy). The aim of this study is to observe that enlargement of the nucleus pulposus followed by herniation, disruption and regenerative proliferation of annulus fibrosus cartilaginous tissues participated in the initiation of ossification of the posterior longitudinal ligament of twy/twy mice.

Posterior retinal contour in adult human anisomyopia

PURPOSE. It is well documented that myopia is associated with an increase in axial length or, more specifically, in vitreous chamber depth. Whether the transverse dimensions of the eye also increase in myopia is relevant to further understanding of its development. METHODS. The posterior retinal surface was localized in two-dimensional space in both eyes of young adult white and Taiwanese-Chinese iso- and anisomyopes (N = 56), from measured keratometry, A-scan ultrasonography, and central and peripheral refraction (±35°) data, with the aid of a computer modeling program designed for this purpose. Anisomyopes had 2 D or more interocular difference in their refractive errors, with mean values in their more myopic eyes of -5.57 D and in their less myopic eyes of -3.25 D, similar to the means of the two isomyopic groups. The derived retinal contours for the more and less myopic eyes were compared by way of investigating ocular shape changes that accompany myopia, in the posterior region of the vitreous chamber. The presence and size of optic disc crescents were also investigated as an index of retinal stretching in myopia. RESULTS. Relative to the less myopic eyes of anisometropic subjects, the more myopic eyes were more elongated and also distorted into a more prolate shape in both the white and Chinese groups. However, the Chinese eyes showed a greater and more uniform relative expansion of the posterior retinal surface in their more myopic eyes, and this was associated with larger optic disc crescents. The changes in the eyes of whites displayed a nasal-temporal axial asymmetry, reflecting greater enlargement of the nasal retinal sector. CONCLUSIONS. Myopia is associated with increased axial length and a prolate shape. This prolate shape is consistent with the proposed idea that axial and transverse dimensions of the eye are regulated differently. The observations that ocular shape changes are larger but more symmetrical in Chinese eyes than in eyes of whites warrant further investigation.

Differential impact of posterior lesions in the left and right hemisphere on visual category learning and generalization to contrast reversal

Hemispheric differences in the learning and generalization of pattern categories were explored in two experiments involving sixteen patients with unilateral posterior, cerebral lesions in the left (LH) or right (RH) hemisphere. In each experiment participants were first trained to criterion in a supervised learning paradigm to categorize a set of patterns that either consisted of simple geometric forms (Experiment 1) or unfamiliar grey-level images (Experiment 2). They were then tested for their ability to generalize acquired categorical knowledge to contrast-reversed versions of the learning patterns. The results showed that RH lesions impeded category learning of unfamiliar grey-level images more severely than LH lesions, whereas this relationship appeared reversed for categories defined by simple geometric forms. With regard to generalization to contrast reversal, categorization performance of LH and RH patients was unaffected in the case of simple geometric forms. However, generalization to of contrast-reversed grey-level images distinctly deteriorated for patients with LH lesions relative to those with RH lesions, with the latter (but not the former) being consistently unable to identify the pattern manipulation. These findings suggest a differential use of contrast information in the representation of pattern categories in the two hemispheres. Such specialization appears in line with previous distinctions between a predominantly lefthemispheric, abstract-analytical and a righthemispheric, specific-holistic representation of object categories, and their prediction of a mandatory representation of contrast polarity in the RH. Some implications for the well-established dissociation of visual disorders for the recognition of faces and letters are discussed.

The retinopathy of prematurity: a study of incidence and the identification of those babies at risk: myopia associated with prematurity

The ocular problems associated with premature birth have been with us ever since it was discovered that the application of high levels of inspired oxygen provided a reduction in mortality. The consequence of this reduction in mortality has been a rise in morbidity; these mortality and morbidity rates have oscillated during the attempt to find a reasonable balance. The use of contemporary technology during the attempt both to understand the premature baby's delicate physiology and to maintain life to younger and lighter babies has not yet produced stability. The incidence of typical retinal maldevelopment, retinopathy of prematurity (RCP), was analysed by serial weekly ophthalmoscopy examinations in a regional special care baby unit, 579 examinations being made on 138 babies. The best instrument for this examination was found to be a compact indirect ophthalmoscope incorporating an inverting eyepiece - the Reichert Jung monocular indirect ophthalmoscope. The optimum time for ocular examination to discover potential ocular morbidity was at 33 weeks post-conceptual age (PCA) with continued examinations to the age of 37 weeks PCA. The babies that were found to be at risk of a significant grade of RCP were found to be of a birth weight of less than 1251 grams or had an estimated gestational age at birth of 30 weeks or less. A refractive state of myopia was found to be the norm. The myopia reduced as life progressed to attain emmetropia around the age of 50 weeks PCA or 22 weeks survival. The reduction of the myopic state was found to be dependent on birth weight and gestational age at birth, the youngest and therefore the lightest being more predictable in attaining emmetropia. Refractive variations were found to be coincident with the timings of certain medical treatment regimes and a hypothesis is postulated as to the mechanism of this association.

The influence of posterior corneal surface astigmatism on residual astigmatism

It has often been found that corneal astigmatism exceeds the amount exhibited by the eye as a whole. This difference is usually referred to as residual astigmatism. Scrutiny of the studies of corneal astigmatismreveal that what has actually been measured is the astigmatic contributionof the anterior corneal surface alone. This anterior surface is easily measured whereas measurement of the posterior corneal surface is much more difficult. A method was therefore developed to measure the radius and toricity of the posterior corneal surface. The method relies upon photography of the first and second Purkinje images in three fixed meridians. Keratometry, comparison of anterior and posterior corneal Purkinje images and pachometricdata were applied to three meridional analysis equations, allowing the posterior corneal surface to be described in sphero-cylindrical form. Measurements were taken from 80 healthy subjects from two distinct age groups. The first consisted of 60 young subjects, mean age 22.04 years and the second consisted of 20 old subjects, mean age 74.64 years. The young group consisted of 28 myopes, 24 emmetropes and 8 hyperopes. The old group consisted of 6 myopes and 14 hyperopes. There was an equal number of males and females in each group. These groupings allowed the study of the effects of age, ametropia and gender on the posterior corneal toricity. The effect of the posterior corneal surface on residual astigmatism was assessed and was found to cause an overall reduction. This reduction was due primarily to the posterior corneal surface being consistently steeper relative to the anterior surface in the vertical meridian compared to the horizontal meridian.

Shape of the posterior vitreous chamber in human emmetropia and myopia

PURPOSE - To compare posterior vitreous chamber shape in myopia to that in emmetropia. METHODS - Both eyes of 55 adult subjects were studied, 27 with emmetropia (MSE =-0.55; <+0.75D; mean +0.09 ±0.36D) and 28 with myopia (MSE -5.87 ±2.31D). Cycloplegic refraction was measured with a Shin Nippon autorefractor and anterior chamber depth and axial length with a Zeiss IOLMaster. Posterior vitreous chamber shapes were determined from T2-weighted MRI (3-Tesla) using procedures previously reported by our laboratory. 3-D surface model coordinates were assigned to nasal, temporal, superior and inferior quadrants and plotted in 2-D to illustrate the composite shape of respective quadrants posterior to the second nodal point. Spherical analogues of chamber shape were constructed to compare relative sphericity between refractive groups and quadrants. RESULTS - Differences in shape occurred in the region posterior to points of maximum globe width and were thus in general accord with an equatorial model of myopic expansion. Shape in emmetropia is categorised distinctly as that of an oblate ellipse and in myopia as an oblate ellipse of significantly less degree such that it approximates to a sphere. There was concordance between shape and retinotopic projection of respective quadrants into right, left, superior and inferior visual fields. CONCLUSIONS - The transition in shape from oblate ellipse to sphere with axial elongation supports the hypothesis that myopia may be a consequence of equatorial restriction associated with biomechanical anomalies of the ciliary apparatus. The synchronisation of quadrant shapes with retinotopic projection suggests that binocular growth is coordinated by processes that operate beyond the optic chiasm.

Higher prevalence of retinopathy in diabetic patients of South Asian ethnicity compared with white Europeans in the community:a cross-sectional study

OBJECTIVE—The purpose of this study was to compare prevalence and risk factors for diabetic retinopathy among U.K. residents of South Asian or white European ethnicity. RESEARCH DESIGN AND METHODS—This was a community-based cross-sectional study involving 10 general practices; 1,035 patients with type 2 diabetes were studied: 421 of South Asian and 614 of white European ethnicity. Diabetic retinopathy, sight-threatening retinopathy, maculopathy, and previous laser photocoagulation therapy were assessed after grading of retinal photographs. Data were collected on risk factors including age, duration, and treatment of diabetes, blood pressures, serum total cholesterol, and A1C. RESULTS—Patients of South Asian ethnicity had significantly higher systolic (144 vs. 137 mmHg, P < 0.0001) and diastolic (84 vs. 74 mmHg, P < 0.0001) blood pressure, A1C (7.9 vs. 7.5%, P < 0.0001), and total cholesterol (4.5 vs. 4.2 mmol/l, P < 0.0001). Diabetic retinopathy was detected in 414 (40%) patients (189 South Asian [45%] versus 225 white European [37%]; P = 0.0078). Sight-threatening retinopathy was detected in 142 (14%) patients (68 South Asian [16%] versus 74 white European [12%]; P = 0.0597). After adjustment for confounders, there were significantly elevated risks of any retinopathy and maculopathy for South Asian versus white European patients. CONCLUSIONS—Patients of South Asian ethnicity had a significantly higher prevalence of diabetic retinopathy and maculopathy, with significantly elevated systolic and diastolic blood pressure, A1C, and total cholesterol; lower attained age; and younger age at diagnosis. Earlier onset of disease and higher levels of modifiable risk factors make early detection of diabetes, annual referral for retinal screening, and intensive risk factor control key elements in addressing this health inequality.

Evaluating digital diabetic retinopathy screening in people aged 90 years and over

Introduction: The English National Screening Programme determines that all people with diabetes aged 12 and over should be screened annually for diabetic retinopathy (DR) until they die. Purpose: This study aimed to evaluate digital DR screening in patients aged 90 and over to establish whether it is appropriate to cease screening at age 90. Methods: A retrospective analysis of 200 randomly selected patients with diabetes aged 90 and over within the Birmingham and Black Country Screening Programme. Results: 179 (90%) patients attended screening at least once after turning 90 years of age. To date, the mean number of screens per person 90+ was two (range 1–6) and the mean age of the first of these screens was 91 years (range 90–98 years). 133 (74%) were put on annual recall after their first screen in their 90’s, of which 58% had no visible DR bilaterally. 38 (21%) were referred to ophthalmology - 35 (92%) for non-DR reasons and three for maculopathy. Of the 133 patients put on annual recall, 75 (56%) were screened at least once more. Seven improved, 36 remained stable, three became unsuitable and 29 deteriorated. Of the latter, 18 patients were referred to ophthalmology; one of these for DR. Conclusion: Patients with diabetes aged 90 and over are at low risk of sight threatening DR and annual screening in this age group may be unnecessary. However, annual screening does provide opportunistic identification.

Is twelve years old an acceptable age at which to begin Diabetic Retinopathy Screening?

Introduction: The English National Screening Programme for diabetic retinopathy (ENSPDR) states that “all people with diabetes aged 12 years and over should be offered screening” Purpose: The audit aims to assess whether the current guideline is suitable and whether diabetes duration should be taken into account when deciding at what age to start screening patients. Method: Retrospective analysis of 143 randomly selected patients aged twelve years or younger who have attended diabetic retinopathy (DR) screening in the Birmingham and Black Country Screening Programme. Results: 98% had Type 1 diabetes and mean visual acuity (VA) was 6/5 (6/4-6/36). 73 were under 12 with 7 the youngest age and 70 were aged 12. Both groups had mean diabetes duration of 5 years (1month-11years). For those under 12, 7/73 (9.6%) had background DR, of these mean diabetes duration was 7 years (6-8) and the youngest aged 8. In those aged 12, 5/70 (7.1%) had background DR; of these mean diabetes duration was 8 years (6-11). In total 12 (8.4%) patients aged 12 years or under developed DR. No patients had retinopathy worse than background changes. One patient was referred to ophthalmology for VAs of 6/12, 6/18 and was diagnosed with optic atrophy so returned to annual screening. Conclusion: The results suggest that the current guideline on when to begin screening should be readdressed as more patients under twelve developed DR than those aged 12. Diabetes duration may help when deciding what age to start screening adolescent patients as DR was not seen in those with disease duration.

What is the prevalence of diabetic macular oedema involving the centre of the macula in patients undergoing digital diabetic retinopathy screening

Free Paper Sessions Design. Retrospective analysis. Purpose. To assess the prevalence of center-involving diabetic macular oedema (CIDMO) and risk factors. Methods. Retrospective review of patients who were screen positive for maculopathy (M1) during 2010 in East and North Birmingham. The CIDMO was diagnosed by qualitative identification of definite foveal oedema on optical coherence tomography (OCT). Results. Out of a total of 15,234 patients screened, 1194 (7.8%) were screen positive for M1 (64% bilateral). A total of 137 (11.5% of M1s) were diagnosed with macular oedema after clinical assessment. The OCT results were available for 123/137; 69 (56.1%) of these had CI-DMO (30 bilateral) which is 0.5% of total screens and 5.8% of those screen positive for M1. In those with CIDMO 60.9% were male and 63.8% Caucasian; 90% had type 2 diabetes and mean diabetes duration was 20 years (SD 9.7, range 2-48). Mean HbA1c was 8.34%±1.69, with 25% having an HbA1c =9%. Furthermore, 62% were on insulin, 67% were on antihypertensive therapy, and 64% were on a cholesterol-lowering drug. A total of 37.7% had an eGFR between 30% and 60% and 5.8% had eGFR <30. The only significant difference between the CIDMO and non-CIDMO group was mean age (67.83±12.26 vs 59.69±15.82; p=0.002). A total of 65.2% of those with CIDMO also had proliferative or preproliferative retinopathy in the worst eye and 68.1% had subsequently been treated with macular laser at the time of data review. Conclusions. The results show that the prevalence of CIDMO in our diabetic population was 0.5%. A significant proportion of macula oedema patients were found to have type 2 diabetes with long disease duration, suboptimal glycemic and hypertensive control, and low eGFR. The data support that medical and diabetic review of CIDMO patients is warranted particularly in the substantial number with poor glycemic control and if intravitreal therapies are indicated.

Proliferative diabetic retinopathy (R3) referrals from the digital diabetic retinopathy screening program:urgency of appointment in the hospital eye service achieved and needed?

DESIGN. Retrospective analysis PURPOSE. To assess the clinical characteristics and outcomes of patients identified with proliferative diabetic retinopathy (PDR) referred from the screening program to the hospital eye services (HES) METHODS. a retrospective analysis of urgently referred PDR cases to Birmingham Heartlands HES from august 2008 until July 2010 RESULTS. 130 urgent diabetic retinopathy referrals were made and reviewed. 103 (68% male, 80% type 2 diabetes) were referred for PDR with a mean age of 59 years, mean diabetes duration of 17.8years. 69% were on insulin treatment at the time of the screening, with mean HbA1c of 10.4% (range-5.7 to 16.5%). 65% of the patients were offered appointments at HES within two weeks after referral from the screening. 50.5% of the patients were seen in the HES within 2 weeks, 22 and 16 % were seen 2-4 and 4-8 weeks after referral respectively. 6 patients never attended ophthalmology examination during the two years of review. Of all the attendees, 56% were booked for pan retinal photocoagulation (PRP) & 9(9.3%) for macular laser respectively on their 1st HES visit. 75% of the patients were newly diagnosed PDR and 26 had previous PRP laser but lost to follow up. 63 patients ( 66%) received either PRP or macular laser treatment (85.7% of which is PRP). 63% of the PRP treatment was performed within a month of first HES attendance. Retinopathy grading discrepancy between the screening program and HES was noted in 20% (21 patients). CONCLUSIONS. This data suggests that the digital screening programme is appropriately identifying high risk patients with PDR with timely PRP laser treatment in the majority of patients but raises concern over patients lost to follow up (hence failsafe tracking of appointment attendance), and review of grading discrepancies between the ophthalmology and screening service.

Impact of senescence and disease on the structural and functional performance of the visual pathway

The diagnosis and monitoring of ocular disease presents considerable clinical difficulties for two main reasons i) the substantial physiological variation of anatomical structure of the visual pathway and ii) constraints due to technical limitations of diagnostic hardware. These are further confounded by difficulties in detecting early loss or change in visual function due to the masking of disease effects, for example, due to a high degree of redundancy in terms of nerve fibre number along the visual pathway. This thesis addresses these issues across three areas of study: 1. Factors influencing retinal thickness measures and their clinical interpretation As the retina is the principal anatomical site for damage associated with visual loss, objective measures of retinal thickness and retinal nerve fibre layer thickness are key to the detection of pathology. In this thesis the ability of optical coherence tomography (OCT) to provide repeatable and reproducible measures of retinal structure at the macula and optic nerve head is investigated. In addition, the normal physiological variations in retinal thickness and retinal nerve fibre layer thickness are explored. Principal findings were: • Macular retinal thickness and optic nerve head measurements are repeatable and reproducible for normal subjects and diseased eyes • Macular and retinal nerve fibre layer thickness around the optic nerve correlate negatively with axial length, suggesting that larger eyes have thinner retinae, potentially making them more susceptible to damage or disease • Foveola retinal thickness increases with age while retinal nerve fibre layer thickness around the optic nerve head decreases with age. Such findings should be considered during examination of the eye with suspect pathology or in long-term disease monitoring 2. Impact of glucose control on retinal anatomy and function in diabetes Diabetes is a major health concern in the UK and worldwide and diabetic retinopathy is a major cause of blindness in the working population. Objective, quantitative measurements of retinal thickness. particularly at the macula provide essential information regarding disease progression and the efficacy of treatment. Functional vision loss in diabetic patients is commonly observed in clinical and experimental studies and is thought to be affected by blood glucose levels. In the first study of its kind, the short term impact of fluctuations in blood glucose levels on retinal structure and function over a 12 hour period in patients with diabetes are investigated. Principal findings were: • Acute fluctuations in blood glucose levels are greater in diabetic patients than normal subjects • The fluctuations in blood glucose levels impact contrast sensitivity scores. SWAP visual fields, intraocular pressure and diastolic pressure. This effect is similar for type 1 and type 2 diabetic patients despite the differences in their physiological status. • Long-term metabolic control in the diabetic patient is a useful predictor in the fluctuation of contrast sensitivity scores. • Large fluctuations in blood glucose levels and/or visual function and structure may be indicative of an increased risk of development or progression of retinopathy 3. Structural and functional damage of the visual pathway in glaucomatous optic neuropathy The glaucomatous eye undergoes a number of well documented pathological changes including retinal nerve fibre loss and optic nerve head damage which is correlated with loss of functional vision. In experimental glaucoma there is evidence that glaucomatous damage extends from retinal ganglion cells in the eye, along the visual pathway, to vision centres in the brain. This thesis explores the effects of glaucoma on retinal nerve fibre layer thickness, ocular anterior anatomy and cortical structure, and its correlates with visual function in humans. Principal findings were: • In the retina, glaucomatous retinal nerve fibre layer loss is less marked with increasing distance from the optic nerve head, suggesting that RNFL examination at a greater distance than traditionally employed may provide invaluable early indicators of glaucomatous damage • Neuroretinal rim area and retrobulbar optic nerve diameter are strong indicators of visual field loss • Grey matter density decreases at a rate of 3.85% per decade. There was no clear evidence of a disease effect • Cortical activation as measured by fMRI was a strong indicator of functional damage in patients with significant neuroretinal rim loss despite relatively modest visual field defects These investigations have shown that the effects of senescence are evident in both the anterior and posterior visual pathway. A variety of anatomical and functional diagnostic protocols for the investigation of damage to the visual pathway in ocular disease are required to maximise understanding of the disease processes and thereby optimising patient care.