Eye Hospital NHS Foundation Trust Research Articles

Outcomes of pseudophakic retinal detachment

To provide data on the outcome of pseudophakic retinal detachment (PRD). In a retrospective case-control study, we identified a consecutive series of 63 298 cataract extractions (45 520 patients) performed in a single institution between 1994 and 2003. We included 249 cases with PRD and 845 controls that had cataract surgery on the same day as cases but without PRD. Outcome measures were the risk of impaired vision (6/18-6/60) or blindness (<6/60). A multinomial logistic regression model evaluated risk factors for impaired vision or blindness, while multivariable regression models measured the relative risk of poor visual outcome for posterior capsule tear (PCT) and PRD. Primary pars plana vitrectomy was performed on 207 (84.5%) of the 245 cases treated with surgery, of which 175 (71.4%) needed one procedure. The final acuity was <6/60 in 62 cases (24.9%) and 34 controls (4.0%). After PRD, the relative risk for a final visual outcome <6/60 was 6.8 [95% confidence interval (CI) 4.3-10.6; p < 0.001], and we estimated that the proportion of blindness attributable to PRD was 1.1% (CI 0.7-1.9%). A PCT prior to a PRD was not associated with an increased risk of macular detachment (p = 0.165), but it did carry an increased risk of blindness [odds ratio 4.8 (CI 2.2-10.2; p < 0.001]. Although a PCT has an adverse effect on visual outcome after cataract surgery, a PRD is the foremost surgery-related risk for a poor visual outcome. Patient education of symptoms and prompt treatment may limit the visual consequences.

Retinal vein occlusion and macular edema &amp;ndash; critical evaluation of the clinical value of ranibizumab

Retinal vein occlusions (RVOs) constitute the second most common cause of retinal vascular disease after diabetic retinopathy, with a prevalence of between 1% and 2% in persons older than 40 years of age. Despite the existence of numerous potential therapeutic options, none is entirely satisfactory, and many patients with RVO suffer irreversible visual loss. Fortunately however, the recent introduction of antivascular endothelial growth factor (VEGF) agents, such as ranibizumab (Lucentis®, Genentech, South San Francisco, CA) and bevacizumab (Avastin®, Genentech), offers a potentially new treatment approach for clinicians managing this disorder. The results of the BRAVO and CRUISE trials have provided the first definitive evidence for the efficacy and safety of ranibizumab in the treatment of RVO. As a result, ranibizumab has recently been approved by the US Food and Drug Administration for the treatment of RVO-associated macular edema. In this review, we provide a critical evaluation of clinical trial data for the safety and efficacy of ranibizumab, and address unresolved issues in the management of this disorder.

Assessment of a new averaging algorithm to increase the sensitivity of axial eye length measurement with optical biometry in eyes with dense cataract

To assess the capability of new software to decrease the proportion of eyes that have insufficient signal-to-noise ratio (SNR) in optical biometry. Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Evaluation of diagnostic test or technology. In a prospective study, consecutive cataract patients coming for biometry who were unsuccessfully measured with the former software (version 4) of the IOLMaster partial coherence interferometry (PCI) device were reevaluated with the new composite software (version 5). Subsequently, in a retrospective study, consecutive cataract patients were measured with software version 5. For unsuccessful scans, the type and intensity of cataract were assessed at the slitlamp. Altogether, 2713 eyes (1956 patients) were included in the study. The prospective study comprised 458 eyes (244 patients), 10.6% of which could not be measured successfully with software version 4. With the composite software, 30% of cases were measured successfully, with a higher proportion (42%) in the posterior subcapsular cataract subgroup. In the retrospective study, of 2255 eyes (1712 patients), 4.7% were not measured successfully using the new algorithm because of white cataract (70 eyes), posterior subcapsular cataract (14 eyes), or dense nuclear cataract combined with posterior subcapsular cataract (13 eyes) or for other reasons (8 eyes). The composite software (version 5) enhanced the SNR, allowing valid measurements in eyes in which optical biometry had previously failed, especially in cases of posterior subcapsular cataract. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.

Rotational stability of a single-piece toric acrylic intraocular lens

To assess the rotational stability of a single-piece toric hydrophobic acrylic intraocular lens (IOL) during the first 6 postoperative months. Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Prospective case series. Eyes with age-related cataract and corneal astigmatism (1.00 to 3.00 D diopter [D]) were measured by partial coherence interferometry (IOLMaster). Preoperatively, the horizontal axis was marked. Surgical technique included a standardized temporal clear corneal incision, phacoemulsification, and in-the-bag implantation of a toric IOL (AcrySof SN60TT). Rotational stability of the IOL was assessed using retroillumination photographs postoperatively at 1 hour and at 1 and 6 months. Uncorrected (UDVA) and corrected distance visual acuities, residual refractive error, and keratometric and refractive cylinders were measured. The study enrolled 30 eyes (30 patients). The mean absolute IOL rotation was 2.44 degrees ± 1.84 (SD) at 1 month and 2.66 ± 1.99 degrees at 6 months. The photographic technique had high reproducibility of axis measurement, with consecutive measurements varying by less than 2.0 degrees. The mean UDVA was 0.16 logMAR (range 0.42 to -0.18 logMAR) at 1 month and 0.20 logMAR (range 0.60 to -0.20 logMAR) at 6 months. The residual refractive cylinder by autorefraction was -0.84 D (range -2.00 to 0.00 D) and -0.80 D (range -1.75 to 0.00 D), respectively. The acrylic toric IOL was rotationally stable within the first 6 months postoperatively. The photographic and axis analysis method to evaluate stability had high reproducibility and detected small changes in rotation.

Reproducibility of intraocular lens decentration and tilt measurement using a clinical Purkinje meter

To determine the reproducibility of intraocular lens (IOL) decentration and tilt measurements with a new Purkinje meter instrument. Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. After pupil dilation, images of pseudophakic eyes with a plate-style IOL (Akreos Adapt) were obtained using a recently developed Purkinje meter. Intraocular lens decentration and tilt were evaluated by analyzing the captured images using a semiobjective method by marking the reflexes in the images and automatic calculation using a dedicated software program. In study 1, examiner 1 examined the eyes first followed by examiner 2. Ten minutes later, examiner 1 performed a second measurement, after which the intraexaminer and interexaminer reproducibility were determined. In study 2, a Purkinje meter was used to measure pseudophakic eyes with slitlamp finding of clinical IOL decentration, IOL tilt, or both. The results were compared with retroillumination photographs and slitlamp findings. In study 1, there was high intraexaminer reproducibility for decentration (r = 0.95) and tilt (r = 0.85) and high interexaminer reproducibility for decentration (r = 0.84) and tilt (r = 0.75). In study 2, even in extreme cases of decentration and/or tilt, the Purkinje meter measurements were possible and appeared to correlate well with slitlamp findings. Acquisition of images in pseudophakic eyes with the Purkinje meter was simple and rapid. The method was highly reliable for 1 examiner and between 2 examiners.

Phacoemulsification in eyes with extreme axial myopia

To determine the outcomes of phacoemulsification of age-related cataract in eyes with extreme axial myopia. Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. This consecutive case series of eyes with an axial length (AL) greater than 30.0 mm was identified retrospectively. Surgical procedure details, complications, and refractive outcome were recorded. The incidence of postoperative retinal detachment (RD) was assessed in a subgroup of eyes without previous RD or vitrectomy. One hundred seventy-seven eyes (124 patients) were identified from a dataset of 6882 cataract procedures; 21 eyes had previous RD or vitrectomy. Intraoperative complications were posterior capsule tear (5 eyes, 2.8%), zonular dehiscence (3 eyes, 1.7%), and anterior capsule tear (2 eyes, 1.1%). At a median follow-up of 25.4 months, 2 (1.3%) of 156 eyes without previous RD or vitrectomy developed RD. The median biometry prediction error in the 156 eyes (88.1%) with an intraocular lens (IOL) was 0.88 diopter (D) (range 0.00 to 5.75 D); 83 eyes (53.2%) were within +/-1.00 D. The median biometry prediction error was greater in the 61 eyes that received a negative-power IOL (1.38 D) than in the 95 eyes that received a plano or positive-power IOL (0.68 D) (P<.001). The incidence of complications after phacoemulsification in eyes with extreme axial myopia was similar to that in previously reported unselected case series. The refractive outcome showed a hyperopic error that increased with AL, an effect that was primarily the result of the eyes that received a negative-power IOL.

Intraoperative Corneal Thickness Measurement Using Optical Coherence Pachymetry and Corneo-Gage Plus Ultrasound Pachymetry

&lt;H4&gt;PURPOSE&lt;/H4&gt; &lt;p&gt;To compare the central corneal thickness measured by online optical coherence pachymetry (OCP) and ultrasound pachymetry in normal cornea.&lt;/p&gt; &lt;H4&gt;METHODS&lt;/H4&gt; &lt;p&gt;Forty-eight right eyes of 48 consecutive patients were enrolled in this prospective study. Central corneal thickness measurements were taken intraoperatively with the online OCP and ultrasound pachymeter before flap creation. The precision repeatability, intraclass correlation coefficient, and correlation of variation for each instrument was calculated. Intraclass correlation coefficient was based on Bland-Altman plot of differences between instruments.&lt;/p&gt; &lt;H4&gt;RESULTS&lt;/H4&gt; &lt;p&gt;Mean central corneal thickness for ultrasound pachymetry and online OCP was 559.45±33.05 µm (range: 475.50 to 650.50 µm) and 521.19±28.97 µm (range: 447.50 to 606.00 µm), respectively. The precision (repeatability) was 7.86 µm and 9.47 µm, respectively. The intraclass correlation coefficient for the ultrasound pachymeter was 0.997 (95% CI, 0.993-0.998) and 0.993 (95% CI, 0.988-0.996) for the online OCP. The coefficient of variance was 0.50% and 0.66%, respectively. The mean difference between ultrasound pachymetry and online OCP was 38.26±9.96 µm. The limits of agreement were: upper=58.19 µm (95% CI, 53.30-63.07 µm) and lower=18.34 µm (95% CI, 13.45-23.22 µm).&lt;/p&gt; &lt;H4&gt;CONCLUSIONS&lt;/H4&gt; &lt;p&gt;Online OCP can be used as a reliable alternative to ultrasound pachymetry as both instruments gave highly repeatable measurements of central corneal thickness. However, measurements using the OCP were consistently lower than those with the ultrasound pachymeter; therefore, the two techniques should not be used interchangeably. Further studies are needed to determine the implications of thinner central corneal thickness measured with online OCP as well as to resolve the systematic differences in measurements by these pachymetric technologies. [&lt;cite&gt;J Refract Surg&lt;/cite&gt;. 2008;24:610-614.]&lt;/p&gt; &lt;h4&gt;ABOUT THE AUTHORS&lt;/h4&gt; &lt;p&gt;From the Department of Ophthalmology, National University Hospital, Singapore (Wang); Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom (Bunce); and The Eye Institute, Tan Tock Seng Hospital, Singapore (Lee).&lt;/p&gt; &lt;p&gt;The authors have no financial or proprietary interest in the materials presented herein.&lt;/p&gt; &lt;p&gt;Correspondence: Jenn-Chyuan Wang, FRCS(Ophth), Dept of Ophthalmology, National University Hospital, Level 3, Main Building, 5 Lower Kent Ridge Rd, Singapore 119074. Tel: 65 67725317; Fax: 65 67777161; E-mail: &lt;a href="mailto:jennwang2003@yahoo.com"&gt;jennwang2003@yahoo.com&lt;/a&gt;&lt;/p&gt; &lt;p&gt;Received: April 11, 2006&lt;/p&gt; &lt;p&gt;Accepted: July 9, 2007&lt;/p&gt; &lt;p&gt;&lt;b&gt;Posted online: January 15, 2008&lt;/b&gt;&lt;/p&gt;

Experimental Assessment of Corneal Anisotropy

To determine the variation of corneal biomechanical properties with anatomical orientation. Strip specimens extracted from fresh porcine corneas were tested under uniaxial tension with strain rates representing static and dynamic loading conditions. The specimens were extracted from the vertical, horizontal, and 45 degrees diagonal directions. The load elongation results were used to derive the stress-strain behavior of each specimen. The average behavior for specimens taken in each anatomical direction was determined along with the effect of strain rate. Specimens from a small number of human corneas were included in the study to verify the findings. Specimens extracted from the vertical direction of porcine and human corneas demonstrated the highest strength (fracture stress) followed by horizontal then diagonal specimens. Vertical specimens were 10% to 20% stronger than horizontal specimens in porcine and human corneas. At low strain rates (1%/min), vertical specimens displayed similar stiffness (resistance to deformation) to horizontal specimens but greater stiffness than diagonal specimens. On increasing the strain rate to 500%/min, the stiffness behavior matched that of strength with vertical specimens being 10% to 20% stiffer than horizontal specimens in porcine and human corneas. The corneal anisotropic behavior is compatible with the preferential orientation of stromal fibrils in the vertical and horizontal directions. Quantifying the effect of this nonuniform fibril organization on corneal anisotropic behavior will be useful in developing numerical models of the cornea for applications where its integrity is compromised such as in simulating refractive surgery procedures.

Spectrum of clear corneal incision cataract wound infection

To describe the presentation, management, and outcome of 5 patients who presented with main-port or side-port wound infection after uneventful clear corneal cataract surgery. Ophthalmic Surgery Centre, Chatswood, and Department of Ophthalmology, Prince of Wales Hospital, Randwick, Australia, and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. This retrospective case series comprised 5 patients who had uneventful clear corneal phacoemulsification surgery and developed either a main-port or side-port wound infection. The clinical features, microbiologic studies, management, and results are reported. The median age of the patients was 79 years. Infection of the main-port incision occurred in 3 cases and of the side port in 2 cases. The patients presented from a few days to several weeks after uneventful phacoemulsification. In 2 cases, the bacteria Pseudomonas aeruginosa and Staphylococcus aureus were isolated. In 1 case, the fungus Aspergillus was isolated and required extensive medical and surgical treatment. In the other 2 cases; empiric antimicrobial therapy was given because no organism was isolated in 1 case, and in the other milder case, microbiological investigations were not performed. Final visual acuity was 6/4 in 2 cases and 6/5, 6/12, and 6/18 in 1 case each. Bacterial or fungal wound infection can present within days or even several weeks following clear corneal cataract surgery. Patients with ocular discomfort or blurred vision after such surgery should be advised to report promptly. Rapid identification and appropriate management of patients with clear corneal wound infection can result in good visual outcomes.