Scott Hau

Diagnostic accuracy of microbial keratitis with in vivo scanning laser confocal microscopy.

Aims To determine the accuracy of diagnosing microbial keratitis by masked medical and non-medical observers using the Heidelberg Retina Tomograph II/Rostock Cornea Module in vivo confocal microscope. Methods Confocal images were selected for 62 eyes with culture- or biopsy-proven infections. The cases comprised 26 Acanthamoeba, 12 fungus, three Microsporidia, two Nocardia and 19 bacterial infections (controls). The reference standard for comparison was a positive tissue diagnosis. These images were assessed on two separate occasions by four observers who were masked to the tissue diagnosis. Diagnostic accuracy indices, κ statistic and percentage agreement values were calculated. The Spearman correlation coefficient (rs) was calculated for the number of correct diagnoses versus duration of disease. Results The highest sensitivity and specificity values were 55.8% and 84.2%, respectively, and the lowest sensitivity and specificity values were 27.9% and 42.1%, respectively. The highest positive and lowest negative likelihood ratios were 2.94 and 0.59, respectively. Agreement values were: fair to moderate (κ 0.22–0.44) for reference standard versus observer diagnosis, moderate to good in intraobserver variability (repeatability, κ 0.56–0.88) and poor to moderate in interobserver variability (reproducibility, κ 0.15–0.47). The correct diagnosis was associated with duration of disease for Acanthamoeba keratitis (rs=0.60, p=0.001). Conclusions The diagnostic accuracy of microbial keratitis by confocal microscopy is dependent on observer experience. Intraobserver repeatability was better than interobserver reproducibility. Difficulty in distinguishing host cells from pathogenic organisms limits the value of confocal microscopy as a stand-alone tool in diagnosing microbial keratitis.

Corneal complications of glaucoma surgery

Purpose of review Most glaucoma surgery can adversely affect the cornea. This often consists of mild endothelial loss on specular microscopy, but occasionally corneal decompensation may occur. The effect on the cornea also depends on preexisting corneal disease, severity and chronicity of intraocular pressure elevation, prior intraocular procedures and complications. With the exception of aqueous shunts, glaucoma procedures are not known to result in progressive endothelial cell loss. Recent findings Corneal problems are most common after aqueous shunts, especially in children, in which tube-endothelial touch is common. However, other corneal effects of glaucoma surgery have also been reported. Antiproliferative drugs have a toxic effect on endothelium that may be reduced by concurrent use of viscoelastics. Subconjunctival mitomycin C injection may cause limbal stem cell deficiency. In combined phacoemulsification and trabeculectomy, a one-site approach induces less endothelial trauma than two sites. Overhanging blebs may induce corneal dissection, and even decompensation. Descemets membrane detachment has been reported after nonpenetrating glaucoma surgery, although less endothelial loss is induced than after trabeculectomy. Summary Corneal complications are commonest in patients with aqueous shunts, and long-term prospective studies of endothelial cell density are required to elucidate the factors that predispose to corneal endothelial cell loss.

Quality of Life in High Myopia before and after Implantable Collamer Lens Implantation

PURPOSE To examine changes in vision-related quality of life after implantable Collamer lens (ICL) implantation for the correction of myopia. DESIGN Prospective, interventional, consecutive case series. PARTICIPANTS We included 34 consecutive patients (68% female; mean age, 37 years [range, 23-49]) with preoperative myopia (mean ± standard deviation [SD] refraction spherical equivalent, -11.0 ± 3.12). INTERVENTION Bilateral ICL implantation. MAIN OUTCOME MEASURES Quality of life Impact of Refractive Correction (QIRC) score. RESULTS The median postoperative interval before questionnaire administration was 4 months (range, 3-7). The QIRC scores were significantly higher postoperatively (preoperative QIRC score [mean ± SD], 40.45 ± 4.83; postoperative QIRC score 53.79 ± 5.60; P < 0.001), with significant improvements (P<0.01) for 14 of 19 items. Nineteen (58%) patients reported a worsening in night vision symptoms (mostly nonspecific glare and halo or arc effects) after surgery, but overall levels of satisfaction were high; 88% were either satisfied or very satisfied with the results of surgery. No patients reported overall dissatisfaction. In free text responses, 11 patients (32%) described ICL implantation as life changing or wished that they had opted for the surgery sooner. CONCLUSIONS Implantation of an ICL for myopia is associated with significant improvements in quality of life. Any dissatisfaction with the procedure largely relates to night vision symptoms, which are common in the early postoperative period.

Microsporidium stromal keratitis: in vivo confocal findings.

Purpose: To relate the clinical signs, histopathologic features, and in vivo confocal biomicroscopy findings of a case of stromal microsporidial keratitis and to describe the use of in vivo confocal microscopy to monitor treatment effect. Methods: An immunocompetent male patient presented with unilateral indolent stromal keratitis. Stromal microsporidiosis was confirmed after corneal biopsy. He underwent examination that used in vivo confocal microscopy (Heidelberg Retina Tomograph II and Rostock Cornea Module) before and after treatment with topical fumagillin and oral albendazole. Clinicopathologic correlation of the confocal scan was performed. Results: Corneal biopsy showed extracellular microsporidium spores aligned along keratocytes and corneal lamellae. In vivo confocal scans showed similar morphology, with bright dots aligned along keratocytes. Treatment with antimicrobials and topical steroid gave resolution of active keratitis, correlating with disappearance of the bright spores on repeat in vivo confocal scanning. Conclusions: The in vivo confocal microscopy appearance of microsporidial keratitis corresponds to the histologic features from biopsy material. Treatment response may be monitored by using this technique, although definitive diagnosis requires corneal biopsy.

Hyperopic shift from posterior migration of hydrophilic acrylic intraocular lens optic

UNLABELLED Two cases that developed a delayed hyperopic shift in refraction following implantation of a single-piece hydrophilic intraocular lens (IOL) are described. The haptics of the Akreos Adapt IOL were flexed anteriorly by capsular contraction, leaving a marked gap between the optic and the anterior capsule. A third case that had marked capsule phimosis and similar anterior flexion of the haptics but with a stable refraction is also described. In this case, the anterior and posterior leaves of the capsule fused peripherally and the IOL optic position was normal. The effective power of an IOL depends on the distance between the apex of the cornea and the center of the optic. Capsule contraction without fusion of the peripheral capsule can make the haptics of this IOL design flex anteriorly with posterior movement of the optic and a hyperopic shift in refraction. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.

Prospective Study of the Diagnostic Accuracy of the In Vivo Laser Scanning Confocal Microscope for Severe Microbial Keratitis

Purpose To determine the diagnostic accuracy of in vivo confocal microscopy (IVCM) for moderate to severe microbial keratitis (MK). Design Double-masked prospective cohort study. Participants Consecutive patients presenting to Aravind Eye Hospital, Madurai, India, between February 2012 and February 2013 with MK (diameter ≥3 mm, excluding descemetocele, perforation, or herpetic keratitis). Methods Following examination, the corneal ulcer was scanned by IVCM (HRT3/RCM, Heidelberg Engineering, Heidelberg, Germany). Images were graded for the presence or absence of fungal hyphae or Acanthamoeba cysts by the confocal microscopist who performed the scan (masked to microbial diagnosis) and 4 other experienced confocal graders (masked to clinical features and microbiology). The regrading of the shuffled image set was performed by 3 graders, 3 weeks later. Corneal-scrape samples were collected for microscopy and culture. Main Outcome Measures The main outcome measures were sensitivity, specificity, and positive and negative predictive values of IVCM compared with those of a reference standard of positive culture or light microscopy. Sensitivities and specificities for multiple graders were pooled and 95% confidence intervals calculated using a bivariate random-effects regression model. Results The study enrolled 239 patients with MK. Fungal infection was detected in 176 (74%) and Acanthamoeba in 17 (7%) by microbiological methods. IVCM had an overall pooled (5 graders) sensitivity of 85.7% (95% confidence interval [CI]: 82.2%–88.6%) and pooled specificity of 81.4% (95% CI: 76.0%–85.9%) for fungal filament detection. For Acanthamoeba, the pooled sensitivity was 88.2% (95% CI: 76.2%–94.6%) and pooled specificity was 98.2% (95% CI: 94.9%–99.3%). Intergrader agreement was good: κ was 0.88 for definite fungus; κ was 0.72 for definite Acanthamoeba. Intragrader repeatability was high for both definite fungus (κ: 0.88–0.95) and definite Acanthamoeba classification (κ: 0.63–0.90). IVCM images from 11 patients were considered by all 5 graders to have a specific organism present (10 fungus, 1 Acanthamoeba) but had negative results via culture and light microscopy. Conclusions Laser scanning IVCM performed with experienced confocal graders has high sensitivity, specificity, and test reproducibility for detecting fungal filaments and Acanthamoeba cysts in moderate to large corneal ulcers in India. This imaging modality was particularly useful for detecting organisms in deep ulcers in which culture and light microscopy results were negative.

Cataract surgery outcome in eyes with keratoconus

Background To review the refractive outcome of cataract surgery in eyes with keratoconus. Methods We retrospectively reviewed the medical records of 64 consecutive patients (92 eyes) who underwent cataract surgery with implantation of a spherical intraocular lens (IOL). We recorded the method of refractive correction and the effect of the keratometry (K) on the biometry prediction error (BPE). Results 35 eyes had mild keratoconus (mean K<48 dioptres (D)), 40 had moderate keratoconus (mean K 48 D to 55 D) and 17 had severe keratoconus (mean K>55 D). Actual K values were used in all eyes with mild or moderate keratoconus with a target refraction of approximately −1.0 D in mild keratoconus and −1.5 D in moderate keratoconus that resulted in a mean BPE of 0.0 D and +0.3 D, respectively. The actual K values were used in eight of the 17 eyes with severe keratoconus with a mean target refraction of −5.4 D, which resulted in a mean BPE of +6.8 D. In the remaining nine eyes, a standard K value of 43.25 D was used with a mean target refraction of −1.8 D, which resulted in a mean BPE of +0.6 D. Conclusions Using the actual K values with a target of low myopia is a suitable option for spherical IOL selection for eyes with a mean K of ≤55 D. When there is severe keratoconus, the use of actual K values can result in a large hyperopic error and the use of standard K value in these eyes should be considered.

Evaluation of iris and iridociliary body lesions with anterior segment optical coherence tomography versus ultrasound B-scan

Aims To compare anterior segment optical coherence tomography (AS-OCT) with ultrasound B-scan (USB) in evaluating iris and iridociliary body lesions. Methods Image features and resolution comparison between AS-OCT and USB in 126 patients (126 eyes) presenting with iris or iridociliary body lesion. Bland–Altman plots were generated to assess the level of agreement between the two techniques. Results The three most common diagnoses were iris naevi (62 (49.2%)), iris pigment epithelial cysts (23 (18.3%)) and iris melanoma (11 (8.7%)). Image feature comparison for USB was better than AS-OCT in visualising all tumour margins (81 (64.3%) vs 59 (46.8%)), posterior tumour margin (54 (42.9%) vs 16 (12.7%)) and producing less posterior shadowing (121 (96%) vs 43 (34.1%)). Image resolution comparison revealed USB to be slightly better for resolving the overall tumour (45 (35.7%) vs 43 (34.1%)) and posterior tumour surface (70 (55.6%) vs 32 (25.4%)) but AS-OCT was better for resolving the anterior (62 (49.2%) vs 4 (3.2%)) and lateral tumour surface (62 (49.2%) vs 31 (24.6%)). Comparing the three most common diagnoses, USB was better for visualising iris pigment epithelial cysts (12 (52.2%) vs 2 (8.7%)) and iris melanoma (7 (63.6%) vs 1 (9.1%)) but AS-OCT was better (28 (45.2%) vs 15 (24.2%)) for visualising iris naevi. Bland–Altman plots showed good agreement between the two techniques for lesions smaller than 3 mm in base and 2 mm in elevation. Conclusions AS-OCT is superior to USB for imaging small lesions pertaining to the anterior iris but USB is better for imaging larger iris lesions with posterior or ciliary body extension.

Corneal Endothelial Morphology in Eyes Implanted With Anterior Chamber Aqueous Shunts

Purpose: To investigate risk factors for lower corneal endothelial cell density after anterior chamber aqueous shunt implantation. Methods: Forty eyes implanted with aqueous shunts were examined using anterior segment optical coherence tomography to document shunt position and specular microscopy for central corneal endothelial cell density (CCED) and peripheral (in the vicinity of the tube) corneal endothelial cell density (PCED). Other clinical parameters relating to shunt implantation were also recorded and analyzed. Results: Mean CCED and PCED were 1537 ± 681 cells per square millimeter and 1310 ± 586 cells per square millimeter. The median follow-up was 36 months (range: 24-72 months) after shunt implantation. There was a significant association among the time from shunt implantation (β coefficient = −0.325; P = 0.040), the degree of peripheral anterior synechiae (PAS) in clock hours (β = −0.439; P = 0.004), and the number of previous operations (β = −0.316; P = 0.047) with CCED, whereas the degree of PAS was the only factor associated with PCED (β = −0.391; P = 0.013) on univariate analysis. Multiple linear regression analysis revealed that the degree of PAS was the only factor associated with CCED (β = −0.351; P = 0.023). There was no correlation between shunt position parameters and corneal cell density. Conclusions: The association between lower corneal cell density and aqueous shunt implantation appeared to be multifactorial, with the degree of PAS to be the most significant. Anterior segment optical coherence tomography is a promising technique for quantifying tube position in the anterior chamber after aqueous shunt implantation.

Presumed corneal argyrosis from occlusive soft contact lenses: a case report.

Purpose: To report a case of presumed corneal argyrosis associated with sliver nitrate-coated cosmetic soft contact lens wear. Methods: A 67-year-old woman wore silver nitrate-coated occlusive soft lenses for 17 years for the management of intractable diplopia. Slit-lamp examination revealed a diffuse blue-gray deposit that was characteristic of corneal argyrosis just anterior to Descemet membrane. Confocal microscopy, anterior segment optical coherence tomography, and noncontact specular microscopy were performed. Results: Confocal microscopy showed hyperreflective granules in Bowman layer, deep stroma, and Descemet membrane. The granules were below the resolution of anterior segment optical coherence tomography. Confocal and specular microscopy showed an abnormal reflection from the region of Descemet membrane. Central corneal endothelial cell density was 2560 cells per square millimeter. Conclusion: Presumed corneal argyrosis can occur after long-term use of silver nitrate-coated contact lenses.