Fook Chang Lam

Serial 3-dimensional computed tomography and a novel method of volumetric analysis for the evaluation of the osteo-odonto-keratoprosthesis.

Purpose: To assess the use of serial computed tomography (CT) in the detection of osteo-odonto-lamina resorption in osteo-odonto-keratoprosthesis (OOKP) and to investigate the use of new volumetric software, Advanced Lung Analysis software (3D-ALA; GE Healthcare), for detecting changes in OOKP laminar volume. Methods: A retrospective assessment of the radiological databases and hospital records was performed for 22 OOKP patients treated at the National OOKP referral center in Brighton, United Kingdom. Three-dimensional surface reconstructions of the OOKP laminae were performed using stored CT data. For the 2-dimensional linear analysis, the linear dimensions of the reconstructed laminae were measured, compared with original measurements taken at the time of surgery, and then assigned a CT grade based on a predetermined resorption grading scale. The volumetric analysis involved calculating the laminar volumes using 3D-ALA. The effectiveness of 2-dimensional linear analysis, volumetric analysis, and clinical examination in detecting laminar resorption was compared. Results: The mean change in laminar volume between the first and second scans was −6.67% (range, +10.13% to −24.86%). CT grades assigned to patients based on laminar dimension measurements remained the same, despite significant changes in laminar volumes. Clinical examination failed to identify 60% of patients who were found to have resorption on volumetric analysis. Conclusions: Currently, the detection of laminar resorption relies on clinical examination and the measurement of laminar dimensions on the 2- and 3-dimensional radiological images. Laminar volume measurement is a useful new addition to the armamentarium. It provides an objective tool that allows for a precise and reproducible assessment of laminar resorption.

Spontaneous perforation of the cornea in mild keratoconus.

Purpose: Spontaneous corneal perforation during acute hydrops in keratoconus is a very rare complication and has only been described in patients with advanced keratoconus. We describe a case of spontaneous corneal perforation in mild keratoconus in a patient with no identifiable risk factors. Methods: We report retrospectively on a 34-year-old woman with mild keratoconus (Krumeich stage II) who presented with the spontaneous perforation of the cornea. A literature review was undertaken. Results: The handful of previously reported cases included patients with advanced keratoconus. Our patient had none of the risk factors identified in previously reported cases (eye rubbing, topical steroid use, and raised intraocular pressures). Corneal gluing was performed to restore globe integrity. She retained a visual acuity of 6/9 even through the acute episode. With the resolution of the acute episode, her corneal astigmatism improved and she achieved a final best-corrected visual acuity of 6/6 with spectacles. Conclusions: To our knowledge, this is the first reported case of spontaneous perforation of the cornea in mild keratoconus. We demonstrate that in this event, a good visual prognosis is possible from gluing alone.

The future of keratoprostheses (artificial corneae)

Corneal blindness is a major cause of blindness in the world, second only to cataract. For many patients, a corneal graft could offer a second chance of sight. However, in some cases (eg, in patients with multiple graft failures, limbal stem cell failure, severe chemical burns and autoimmune diseases such as Stevens–Johnson syndrome) the ocular environment is too hostile for a corneal graft. Keratoprostheses offer these patients the hope and prospect of visual rehabilitation. With modern advancements, many exciting developments are in store for the future of the keratoprosthesis (KPro). The idea of an artificial cornea or a KPro was first introduced by the French ophthalmologist, Guillaume Pellier de Quengsy, in 1789. The first published surgical case was in 1853 by Nussbaum who implanted a quartz crystal into the cornea.1 The prosthesis was retained for 6 months. Further attempts at refining keratoprostheses were associated with a high rate of failure with tissue necrosis, leakage, infection and extrusion of the device.2 Interest in keratoprostheses waned when Zirm performed the first successful human-to-human corneal graft in 1906. However, there was renewed interest when it was found during World War II that polymethylmethacrylate (PMMA) splinters embedded in the corneae of pilots were well tolerated. Many KPros …

Peripheral ulcerative keratitis due to a ‘long lost’ hard contact lens

Peripheral ulcerative keratitis (PUK) is a disorder consisting of a crescent‐shaped destructive inflammation of the perilimbal corneal stroma. PUK can occur in a variety of ocular and systemic conditions including infections, lid abnormalities, dermatological disorders and connective tissue disorders. We present a case of PUK associated with a hard contact lens (CL) retained in the superior fornix for over 16 years. After removal of the embedded CL, a superior forniceal conjunctival pedicle graft was performed to prevent corneal perforation. The patient was managed postoperatively with a combination of topical steroids and antibiotics. The use of systemic immunosuppressive therapy was not necessary. Micro‐trauma and micro‐keratitis may have occurred as a result of the mechanical effect of the CL but if this was the sole mechanism, one would expect presentation at a much earlier date. We discuss the pathogenetic mechanisms which may have contributed to the development of this ulceration. This report highlights the importance of lid eversion when examining patients with anterior segment pathology.

Suturing techniques and postoperative management in penetrating keratoplasty in the United Kingdom

Aims To report on the suturing techniques and aspects of postoperative management in penetrating keratoplasty in the United Kingdom. Methods A postal questionnaire was sent to 137 ophthalmic consultants identified from a Royal College of Ophthalmology database as having a special interest in anterior segment surgery. The questionnaire surveyed surgeon preferences for surgical and suturing technique for penetrating keratoplasty surgery, and the postoperative care of corneal grafts. Results In all, 68% of questionnaires were completed and returned: 73% of respondents used a Flieringa ring or equivalent, 94% routinely used cardinal sutures, with 50.5% removing them at the end of the procedure. The most common suturing technique for routine penetrating keratoplasty was a single continuous suture (35%). In these cases, a 10/0 nylon suture was used by 89%. Sixty-six percent changed their technique in high-risk cases, 52% used a 3-1-1 knot, and 75% made a distinction between a reef and granny knot, with 76% using a reef. Thirty percent buried the knots within the donor material, and 29% within the host tissue. Twenty-five percent had no routine time for graft suture removal, but 41% removed them between 1 and 2 years post-surgery. After suture removal, 98% used steroids and 88% used topical antibiotics. Thirty-four percent stopped topical steroids before suture removal, with 38% stopping topical steroids more than 3 months prior to suture removal. Conclusion This survey demonstrates that there is considerable variation in suturing techniques and postoperative care for penetrating keratoplasty. These significant variations in practice need to be considered when interpreting outcomes and research.

Black-on-clear piggyback technique for a black occlusive intraocular device in intractable diplopia

Black occlusive intraocular devices have been used successfully for intractable binocular diplopia. We describe a novel technique of implanting both a black occlusive device and a clear poly(methyl methacrylate) intraocular lens (IOL) in the capsular bag during phacoemulsification surgery. If the need should arise at a later date, this approach will allow safer and easier explantation of the black occlusive device, avoiding the need for IOL exchange.

Optical functional performance of the osteo-odonto-keratoprosthesis

Purpose: The aim of this study was to evaluate optical and visual functional performance of the osteo-odonto-keratoprosthesis (OOKP). Methods: Optical design and analysis was performed with customized optical design software. Nine patients with implanted OOKP devices and 9 age-matched control patients were assessed. Contrast sensitivity was assessed and glare effect was measured with a brightness acuity test. All OOKP patients underwent kinetic Goldmann perimetry and wavefront aberrometry and completed the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). Results: Optical analysis showed that the optical cylinder is near diffraction-limited. A reduction in median visual acuity (VA) with increasing glare settings was observed from 0.04 logMAR (without glare) to 0.20 logMAR (with glare at “high” setting) and significantly reduced statistically when compared with the control group at all levels of glare (P < 0.05). Contrast sensitivity was significantly reduced when compared with age-matched controls at medium and high spatial frequencies (P < 0.05). Median Goldmann perimetry was 65 degrees (interquartile range, 64–74 degrees; V-4e isopters) and 69 degrees excluding 2 glaucomatous subjects. Several vision-related NEI VFQ-25 subscales correlated significantly with VA at various brightness acuity test levels and contrast sensitivity at medium spatial frequencies, including dependency, general vision, near activities and distance activities. Conclusions: The OOKP optical cylinder provides patients with a good level of VA that is significantly reduced by glare. We have shown in vivo that updates to the optical cylinder design have improved the patients field of view. Reduction of glare and refinement of cylinder alignment methods may further improve visual function and patient satisfaction.