The limbal vasculature.

The cornea is an avascular structure whose closest point of approach to the systemic blood stream is provided by the limbal vessels. Activity within these structures provides the clinician with a sensitive indicator of contact lens performance and associated problems. In this paper, the anatomy and physiology of the limbal vessels is reviewed with particular attention to the control of capillary perfusion. Mechanisms whereby soft contact lenses can interact with this network of vessels are considered.     

Paediatric idiopathic limbal stem cell deficiency

Acquired limbal stem cell deficiency (LSCD) describes a condition in which the corneal limbal stem cells are altered or destroyed, typically due to ocular trauma, chronic allergy or inflammation. Idiopathic LSCD is a term used to describe limbal stem cell failure in the absence of any identifiable causative factor. While several cases of adult-onset LSCD have been identified previously, this case report describes a rare presentation of bilateral asymmetric idiopathic paediatric limbal stem cell deficiency in a sixteen-year-old male with an otherwise unremarkable ocular history.     

Corneo-scleral limbal changes following short-term soft contact lens wear

Purpose

To assess whether short-term soft contact lens wear alters the anterior eye surface.

The influence of limbal and scleral shape on scleral lens design

Purpose

To summarize the research findings on the ocular surface profile, to provide a definition and a classification of the corneoscleral shape, and to offer guidelines in selecting scleral lens design.

Intrasession repeatability of corneal,limbal and scleral measurements obtained with a fourier transform profilometer

PurposeTo evaluate the intrasession repeatability of corneal, limbal and scleral measurements obtained by an experienced operator with a Fourier transform profilometer in healthy eyes.MethodsProspective, single-center study including 35 eyes of 35 participants with ages ranging from 13 to 52 years. All patients underwent three consecutive corneoscleral topographic evaluations with the Eye Surface Profiler (ESP) system (Eaglet Eye b.v.). Intrasession repeatability was analyzed for different geometric and sagittal height variables using the following parameters: the within-subject standard deviation (S_w) of the three consecutive measurements, intrasubject precision (1.96 × S_w), coefficient of variation (CV) and the intraclass correlation coefficient (ICC).ResultsInner best fit sphere (BFS) showed good repeatability, with ICC of 0.844. Higher variability was observed for the repeated measurements of limbus and outer BFS, with ICCs of 0.636 and 0.739, respectively. For mean corneal and scleral radius, ICCs were 0.933 and 0.888, respectively. The repeatability of all sagittal height data was good for all chords evaluated (11–15 mm), with Sw values from 0.02 to 0.11 mm, and ICCs from 0.568 to 0.909. A significant positive correlation was found between the magnitude of temporal-nasal sagittal height difference for all measured chords and its S_w associated.ConclusionThe ESP system can provide consistent measurements of sagittal height data for different chord diameters as well as for mean corneal and scleral radius in healthy eyes. Best fit approaches for limbal and scleral areas were less repeatable, although within a clinically acceptable range.     

Clinical outcomes and complications of fluid-filled scleral lens devices for the management of limbal stem cell deficiency

AimsTo evaluate the clinical and visual outcomes of fluid-filled scleral lens devices (SL) wear in patients with limbal stem cell deficiency (LSCD).DesignRetrospective consecutive case series.Methods27 eyes with LSCD confirmed by in vivo confocal microscopy at the Stein Eye Institute and fitted with SL were included. Correlations between corrected distance visual acuity (CDVA) and LSCD stage determined by clinical grading were performed between baseline (after the SL fit) and the last follow-up (the time of discontinuation of SL wear or the last visit in eyes in which SL were continued). In a subset of patients that had worsened LSCD while using SL, anterior segment optical coherence tomography (AS-OCT) and anterior segment fluorescein angiogram (AS-FA) were performed.ResultsBaseline LSCD grading was stage I in 12 eyes (44.4%), stage 2 in 12 eyes (44.4%), and stage III in 3 eyes (11.1%). At the last follow-up, CDVA was improved in 7 eyes (25.9%), remained stable in 13 eyes (48.1%) and decreased in 7 eyes (25.9%, P = 0.16). The LSCD stage was improved in 7 eyes (25.9%), remained stable in 8 eyes (29.6%) and worsened in 12 eyes (44.4%, P = 0.10). AS-OCT and AS-FA, performed in 5 eyes, showed limbal compression and delayed fluorescein filling.ConclusionSL can improve visual acuity and maintain the ocular surface in the majority of eyes. Worsening of the ocular surface might be a result of limbal hypoxia. Close monitoring of SL fit is necessary in these compromised eyes.     

A pilot study investigating the effect of extended contact lens wear on limbal and central corneal morphology

PurposeTo investigate the effect of long-term extended soft contact lens wear on limbal and central corneal cell morphology, and limbal architecture.MethodsEach participant attended a study visit involving in vivo confocal microscopy of central corneal and limbal epithelium. Scans were graded by five masked graders for three features: central epithelial irregularity, limbal epithelial irregularity and the prominence of palisades of Vogt. The variability of grades between different graders and the difference of grades between extended wearers and daily soft/non-contact lens wearers were assessed.ResultsNineteen participants (9 extended soft contact lens wearers and 10 daily soft/non-contact lens wearers) aged 31–65 years were enrolled in this study. Scans from 37 eyes were included in the analysis. Agreement between graders for each feature was moderate to good with inter class correlation >0.7. While there were no significant differences in central epithelial cell irregularity (p = 0.527) and the prominence of palisade of Vogt (p = 0.182) between extended or daily soft/non-contact lens wearers, limbal epithelial cell irregularity showed a trend with increased irregularity in extended soft contact lens wearers (p = 0.091).ConclusionsWhile no differences in limbal cell morphology and structure or central epithelial cell was found in this subjective grading study of extended wearers compared to daily soft/non-contact lens wearers, further studies using a larger sample size or a longitudinal study design are warranted.