Sorcha Ní Dhubhghaill

Normative Values for Corneal Densitometry Analysis by Scheimpflug Optical Assessment

PURPOSE To describe the normative data for corneal Scheimpflug densitometry based on a cohort of normal participants. METHODS A total of 445 healthy participants were recruited for assessment (794 eyes). Left and right eyes were considered separately. All participants were assessed using the corneal densitometry analysis add-on to the standard software of the Oculus Pentacam. Densitometry measurements were obtained and expressed in standardized grayscale units (GSU). RESULTS All participants were Caucasian; 42% were male and 58% were female. The mean age was 48.0 ± 15.3 years (range, 20.2-84.2 years). Mean corneal densitometry over the 12-mm-diameter area was 19.74 ± 3.89 GSU. When divided by radial zone, densitometry values were lowest in the central zone (16.76 ± 1.87 GSU) and highest in the periphery (27.36 ± 7.47 GSU). There was no difference between central zone and the surrounding 2- to 6-mm annulus (P > 0.05), though the 6- to 10-mm and the 10- to 12-mm zones displayed higher densitometry values (P < 0.001). When divided by depth, the anterior layer displayed the highest densitometry reading of 25.81 ± 5.14 GSU, which was significantly higher than that of both the central (P < 0.001) and the posterior layers (P < 0.001). Changes in corneal densitometry were correlated with age, though not within the central 6-mm-diameter ring. No sex difference was seen within the cohort. CONCLUSIONS This add-on to the standard imaging software allows rapid and objective assessment of the corneal densitometry. We provide normative data that may be used as a reference facilitating research and complementing clinical examination.

Limbal Stem Cell Deficiency: Current Treatment Options and Emerging Therapies.

Severe ocular surface disease can result in limbal stem cell deficiency (LSCD), a condition leading to decreased visual acuity, photophobia, and ocular pain. To restore the ocular surface in advanced stem cell deficient corneas, an autologous or allogenic limbal stem cell transplantation is performed. In recent years, the risk of secondary LSCD due to removal of large limbal grafts has been significantly reduced by the optimization of cultivated limbal epithelial transplantation (CLET). Despite the great successes of CLET, there still is room for improvement as overall success rate is 70% and visual acuity often remains suboptimal after successful transplantation. Simple limbal epithelial transplantation reports higher success rates but has not been performed in as many patients yet. This review focuses on limbal epithelial stem cells and the pathophysiology of LSCD. State-of-the-art therapeutic management of LSCD is described, and new and evolving techniques in ocular surface regeneration are being discussed, in particular, advantages and disadvantages of alternative cell scaffolds and cell sources for cell based ocular surface reconstruction.

Repeatability and Inter-device Agreement for Three Different Methods of Keratometry: Placido, Scheimpflug, and Color LED Corneal Topography

PURPOSE To determine the repeatability of a color LED corneal topographer (Cassini; iOptics, The Hague, The Netherlands) and compare it with Placido and Scheimpflug based devices (EyeSys 2000; EyeSys Laboratories, Houston, TX, and Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany). METHODS This prospective study involved 20 healthy volunteers (20 eyes) recruited from the staff of the Antwerp University Hospital. For each eye, three measurements were taken using each device, from which eight parameters describing keratometry and astigmatism were derived. Repeatability was assessed using intrasession, within-subject analysis of variance. Agreement was evaluated between pairs of devices with Bland- Altman plots and 95% confidence intervals. RESULTS The repeatability values were good for all three devices, although slightly worse for the Cassini than for the other two devices for steep, flat, and mean keratometry. The EyeSys showed worse repeatability for the astigmatism axis. EyeSys and Pentacam agreed well with each other in terms of mean keratometry, whereas the Cassini gave consistently higher values by 0.52 diopters (D) when compared with the EyeSys (P < .05, paired t test) and by 0.38 D when compared with the Pentacam (P < .05, paired t test). The Cassini provided similar repeatability values (2.31°) for the astigmatism axis to the Pentacam (2.22°), in contrast to the EyeSys, which produced much more variable axes (9.0°) (P < .05, paired t test). CONCLUSIONS Overall, the three devices display comparable repeatability. The one exception is the astigmatism axis measurement of the EyeSys. The Cassini provides higher keratometry values than the other two devices, but the astigmatism axis agrees well with that provided by the Pentacam.

Pediatric bag-in-the-lens intraocular lens implantation: Long-term follow-up

Purpose To evaluate long‐term follow‐up results of pediatric cataract surgery using the bag‐in‐the‐lens (BIL) intraocular lens (IOL) implantation technique. Setting Antwerp University Hospital, Edegem, Antwerp, Belgium. Design Prospective case series. Methods All pediatric cataract surgeries with BIL IOL implantation performed at the Antwerp University Hospital were evaluated. Only cases that completed a follow‐up of 5 years at the hospital’s Department of Ophthalmology were included in this study. Results Forty‐six eyes of 31 children had a complete follow‐up of 5 years or more after BIL IOL implantation. Sixteen cases were unilateral and 15 were bilateral. Patient age at time of surgery ranged from 2 months to 14 years. The mean refraction at the end of follow‐up was −1.99 diopters (D) ± 3.70 (SD). In bilateral cases, a corrected distance visual acuity (CDVA) of better than 0.5 was attained in 86.7% and a CDVA of 1.0 was achieved in 56.7%. In unilateral cases, 31.2% achieved a CDVA of better than 0.5 but none obtained a CDVA of 1.0. A clear visual axis was maintained in 91.3% of cases during follow‐up. Visual axis reopacification was detected in 4 eyes of 3 cases, all due to inadequate BIL IOL positioning. None of these eyes needed more than 1 intervention to maintain visual axis clarity. Other than 1 case of glaucoma, no severe complications were detected. Conclusion Long‐term follow‐up results show that BIL IOL implantation is a safe, well‐tolerated approach for treating pediatric cataract with a very low rate of visual axis reopacification and a low rate of secondary interventions for other postoperative complications. Financial Disclosure Dr. Tassignon has intellectual property rights to the bag‐in‐the‐lens intraocular lens (U.S. patent 6 027 531; EU patent 009406794.PCT/120268), which is licensed to Morcher GmbH, Stuttgart, Germany. No other author has a financial or proprietary interest in any material or method mentioned.

Atypical sino-orbital inflammatory myofibroblastic tumor with bone and cerebral invasion extending to the orbit

Purpose To report the case of an atypical sino-orbital inflammatory myofibroblastic tumor. Methods Case report. Results A 71-year-old man presented slowly progressive painless diplopia followed by unilateral proptosis of the left eye with slight edema of the upper eyelid. Visual acuity was 0.4 with a relative afferent pupillary defect (RAPD). Abduction and depression of the left eye were limited. Imaging showed a left sino-orbital tumor with mass effect on the medial rectus muscle resulting in proptosis. The lesion showed intracranial extension through the superior orbital fissure with bone erosion and sclerotic bone reaction. Endoscopic ethmoidal, maxillary, and orbital biopsies revealed an inflammatory myofibroblastic tumor. Full blood count showed an eosinophilia while antineutrophil cytoplasmic antibodies and C-reactive protein were negative. To date, 7 cases of orbital myofibroblastic tumor have been described, though none of the prior studies have described bone invasion. Conclusions This erosive sino-orbital inflammatory myofibroblastic tumor is a novel finding mimicking a malignant tumor.

A method for quantifying limbal stem cell niches using OCT imaging

Aims To evaluate the efficacy of Fourier domain-optical coherence tomography (FD-OCT) in imaging and quantifying the limbal palisades of Vogt and to correlate these images with histological findings. Methods The superior and inferior limbal region of both eyes of 50 healthy volunteers were imaged by FD-OCT. Images were processed and analysed using Matlab software. In vitro immunofluorescent staining of a cadaveric donor limbus was analysed to correlate the presence of stem cells in the visualised structures. Results FD-OCT could successfully visualise limbal crypts and the palisades of Vogt in the limbus region. Fluorescent labelling confirmed the presence of stem cells in these structures. The mean palisade ridge width (ΔPR) and the mean interpalisade epithelial rete peg width (ΔERP) were both of the order of 72 μm, leading to a palisade density (PD) of about 7.4 palisades/mm. A significant difference in ΔPR, ΔERP and PD was seen between the inferior and superior sides of the right eye and the superior sides of the left and right eye(p<0.05.). A significant influence of iris colour on parameters ΔPR, ΔERP and PD was found, and of age on PD and ΔERP (p<0.05). Conclusions In vivo OCT imaging is a safe and effective modality to image the limbus and can be used to visualise the palisades of Vogt. Image processing using Matlab software enabled quantification and density calculation of imaged limbal palisades of Vogt. This technique may enhance targeted limbal biopsies for transplantation.

Corneal regeneration: A review of stromal replacements

Corneal blindness is traditionally treated by transplantation of a donor cornea, or in severe cases by implantation of an artificial cornea or keratoprosthesis. Due to severe donor shortages and the risks of complications that come with artificial corneas, tissue engineering in ophthalmology has become more focused on regenerative strategies using biocompatible materials either with or without cells. The stroma makes up the bulk of the corneal thickness and mainly consists of a tightly interwoven network of collagen type I, making it notoriously difficult to recreate in a laboratory setting. Despite the challenges that come with corneal stromal tissue engineering, there has recently been enormous progress in this field. A large number of research groups are working towards developing the ideal biomimetic, cytocompatible and transplantable stromal replacement. Here we provide an overview of the approaches directed towards tissue engineering the corneal stroma, from classical collagen gels, films and sponges to less traditional components such as silk, fish scales, gelatin and polymers. The perfect stromal replacement has yet to be identified and future research should be directed at combined approaches, in order to not only host native stromal cells but also restore functionality. STATEMENT OF SIGNIFICANCE In the field of tissue engineering and regenerative medicine in ophthalmology the focus has shifted towards a common goal: to restore the corneal stroma and thereby provide a new treatment option for patients who are currently blind due to corneal opacification. Currently the waiting lists for corneal transplantation include more than 10 million patients, due to severe donor shortages. Alternatives to the transplantation of a donor cornea include the use of artificial cornea, but these are by no means biomimetic and therefore do not provide good outcomes. In recent years a lot of work has gone into the development of tissue engineered scaffolds and other biomaterials suitable to replace the native stromal tissue. Looking at all the different approaches separately is a daunting task and up until now there was no review article in which every approach is discussed. This review does include all approaches, from classical tissue engineering with collagen to the use of various alternative biomaterials and even fish scales. Therefore, this review can serve as a reference work for those starting in the field and but also to stimulate collaborative efforts in the future.

Intraocular lens exchange technique for an opacified bag-in-the-lens.

We describe the intraocular lens (IOL) exchange technique that is specific to the bag-in-the-lens IOL. The subsequent IOL analysis displayed a deep granular opacification consisting predominantly of calcium and phosphates that has been described in hydrophilic IOLs.

Incidence of rhegmatogenous retinal detachment after bag-in-the-lens intraocular lens implantation.

Purpose To determine the incidence of rhegmatogenous retinal detachment (RRD) and associated risk factors after phacoemulsification and bag‐in‐the‐lens intraocular lens (IOL) implantation. Setting Antwerp University Hospital, Department of Ophthalmology, Antwerp, Belgium. Design Prospective cohort study. Methods All consecutive bag‐in‐the‐lens IOL implantations performed between January 2001 and December 2007 were included, with the exception of combined procedures and IOL exchanges. The retinal detachment (RD) incidence was studied in the total cohort, in a subgroup of patients with 1 to 5 years of follow‐up, and finally in the group remaining after exclusion of all risk factors except gender. Results RD after bag‐in‐the‐lens IOL implantation in 1323 eyes with an average follow‐up of 44.75 months (range 0 to 152 months) was found in 19 eyes (1.44%). The 1‐year RD incidence was 0.49% (5 RD cases in 1024 eyes) (0.00% in patients without risk factors). The 2‐year cumulative RD incidence was 0.84% (9 RD cases in 931 eyes; 0.15% without risk factors). Four clinically significant risk factors were confirmed: male gender, young age at time of surgery (<60 years), axial myopia (axial length ≥25 mm), and history of contralateral RD in the total cohort. Conclusion The RRD incidence following bag‐in‐the‐lens IOL implantation was comparable to that seen after lens‐in‐the‐bag (LIB) implantation. The wide variation in study design in the literature precludes direct comparison, so there is a need for standardization in evaluating RRD incidence after cataract surgery. Future prospective studies should consider patients with and without risk factors (except gender) separately. Financial Disclosure Prof. dr. M.J. Tassignon has intellectual property rights to the bag‐in‐the‐lens intraocular lens (U.S. patent 6 027 531; EU patent 009406794; PCT/120268), which is licensed to Morcher GmbH, Stuttgart, Germany.

Bean-shaped ring segments for capsule stretching and centration of bag-in-the-lens cataract surgery

The bag-in-the-lens (BIL) is a unique approach to IOL placement in cataract surgery. The BIL intraocular lens (IOL) is suspended centrally, supported by the anterior and posterior capsulorhexes. The placement confers a high degree of centration and stability; however, it is dependent on capsular and zonular integrity. In this report, we describe a patient with posttraumatic cataract featuring a sector of iris and suspensory zonule loss. The insertion of custom-designed bean-shaped segments provides capsular tension over the area of defect and a central aperture designed to support the BIL IOL.