Serial intraocular lens opacifications of different designs from the same manufacturer: Clinical and light microscopic results of 71 explant cases.

PURPOSE: To report clinical findings and light microscopic results of 71 opacified hydrophilic acrylic intraocular lenses (IOLs). SETTING: Vivantes Klinikum Neukoelln, Ophthalmology Department, Berlin, Germany. DESIGN: Retrospective case series. METHODS: Sixty-three patients (71 eyes) were referred to the clinic because of vision-impairing IOL opacification between December 2012 and September 2016 after routine cataract surgery elsewhere. The explanted IOLs were analyzed with light microscopy at the John A. Moran Eye Center (University of Utah, Salt Lake City, Utah, USA). Medical records were reviewed for visual acuity, comorbidities, and complications. Clinical follow up was 6 months. RESULTS: Seventy-one opacified 1-piece or 3-piece hydrophilic acrylic IOLs (Lentis) of different designs from 2009 to 2012 (LS-502-1, LS-402-1Y, LS 312-1Y, LS-313-1Y, L-402, L-312) were found. Morphological findings were surface, subsurface, or deep calcifications of the IOL material. Explantation was performed 4 years ± 1.2 (SD) after initial phacoemulsification. The mean patient age was 78.6 ± 8.2 years. Ocular and systemic comorbidities were found without statistical correlation: the most frequent were diabetes, uveitis, and glaucoma. The preoperative mean corrected distance visual acuity changed from 0.63 ± 0.47 logarithm of the minimum angle of resolution (logMAR) to 0.20 ± 0.28 logMAR postoperatively (P < .001). CONCLUSIONS: Different designs of IOLs by the same manufacturer, implanted between 2009 and 2012, developed late calcification with significant visual loss after routine cataract surgery. No medical, surgical, or ophthalmologic trigger could be determined. A manufacture issue might be the reason for the opacification.

Trabecular microbypass stents as minimally invasive approach after conventional glaucoma filtration surgery.

PURPOSE: To evaluate long-term efficacy and safety of 2 trabecular microbypass stents in patients with advanced primary open-angle glaucoma (POAG) and insufficient intraocular pressure (IOP) after previous filtration surgery. SETTING: Vivantes Klinikum Neukölln, Augenklinik, Berlin, Germany. DESIGN: Retrospective case series. METHODS: Eyes with uncontrolled and advanced POAG since 2014 were assessed. All eyes previously had at least 1 filtration surgery procedure. The anatomical landmarks and configuration of the anterior chamber angle had to be identified easily. Two iStents were placed nasally into Schlemm canal. RESULTS: The study comprised 42 patients (42 eyes); 18 eyes had 1 previous glaucoma filtration surgery. During the follow-up of 12 months, the mean IOP in cases of primary failure of filtration surgery decreased from preoperative 23.8 mm Hg ± 3.9 (SD) to 15.2 ± 2.7 mm Hg. For cases with more than 1 previous filtration surgery, the mean IOP decreased from preoperative 26.1 ± 5.7 mm Hg to 16.3 ± 3.3 mm Hg. Medications were reduced from 2.7 ± 0.9 to 2.0 ± 1.1. No intraoperative or perioperative complications occurred. CONCLUSIONS: For eyes with previous filtration surgery and medically uncontrolled IOP, the implantation of 2 stents provided a minimally invasive and safe reduction of mean IOP to less than 18 mm Hg at 12 months. The number of medications was also reduced.

Biometric evaluation of keratoconic eyes with slit lamp-adapted optical coherence tomography.

PURPOSE: To evaluate slit lamp-adapted optical coherence tomography for morphological imaging and morphometrical measurements in keratoconic eyes. METHODS: Using slit lamp-adapted optical coherence tomography, we examined 32 eyes of 20 consecutive patients with keratoconus and described morphological attributes of the cornea. Furthermore, in a subgroup of 19 eyes, we measured morphometrical values of the cornea and compared these values with those of an age-matched control group of 19 normal eyes. RESULTS: Of the 32 keratoconic eyes, 23 eyes had marked corneal thinning of less than 450 µm, 18 eyes had central stromal scarring, and 3 eyes had intrastromal cysts from acute hydrops formation. Central corneal thickness was measured as 374 ± 106 µm in the group of 19 keratoconic eyes, compared with 503 ± 127 µm in the control group (P < 0.05); anterior chamber depth was 3.6 ± 0.4 mm versus 3.1 ± 0.4 mm (P < 0.05); anterior curvature mean radius was 7.2 ± 1.2 mm versus 8.6 ± 1.0 mm (P < 0.05); posterior radius was 5.5 ± 0.7 mm versus 6.8 ± 0.7 mm (P < 0.05). CONCLUSIONS: This study provides further validation that anterior segment optical coherence tomography is a reliable method to assess important parameters for diagnosis and therapeutic outcome control of patients with keratoconus. This method may be particularly useful as a safe and well-defined preoperative diagnostic tool before keratoplasty or corneal cross-linking.

Significance of the riboflavin film in corneal collagen crosslinking.

PURPOSE: To evaluate the role of the preocular riboflavin film in ultraviolet-A (UVA) absorption in corneal collagen crosslinking (CXL). SETTING: Eye Laser Institute, Department of Ophthalmology, Martin-Luther-University, Halle, Germany. METHODS: The absorption of UVA light was measured in human donor and porcine postmortem corneas with and without riboflavin film using 3 solutions: standard dextran-riboflavin, methylcellulose-riboflavin, and hypoosmolar riboflavin-sodium chloride without dextran. The breakup time of the solutions and their absorbance were also determined. RESULTS: After 30-minute instillation of riboflavin solution, the corneal absorption coefficient of the combined stroma-riboflavin film system was 56.36 cm(-1) in human corneas and 51.46 cm(-1) in porcine corneas using dextran-riboflavin; 69.87 cm(-1) and 53.86 cm(-1), respectively, using methylcellulose-riboflavin; and 48.19 cm(-1) and 42.68 cm(-1), respectively, using hypoosmolar riboflavin. For the stroma alone without riboflavin film, the absorption coefficient was reduced to 36.95 cm(-1) in human corneas and 28.91 cm(-1) in porcine corneas using dextran-riboflavin; 38.26 cm(-1) and 32.49 cm(-1), respectively, using methylcellulose-riboflavin; and 38.88 cm(-1) and 28.42 cm(-1), respectively, using hypoosmolar riboflavin solution. The breakup time was 22 minutes for the dextran-riboflavin film, 32 minutes for methylcellulose, and 90 seconds for the hypoosmolar solution. CONCLUSION: Results indicate that the cornea including the riboflavin film can be considered a composite 2-compartment system and that the riboflavin film is an integral part of the CXL procedure and important in achieving the correct stromal and endothelial UVA irradiance. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Potential use of riboflavin/UVA cross-linking in bullous keratopathy.

BACKGROUND: Collagen cross-linking of the cornea has been shown by us to have an antiedematous effect in the cornea. The aim of the present study was to examine if this effect can be used for the treatment of bullous keratopathy. METHODS: This clinical interventional case series included 3 patients (3 eyes) with bullous keratopathy due to pseudophakia, corneal transplant rejection, and Fuchs' endothelial dystrophy. After dehydration for 1 day using 40% glucose, the central 8 mm of the cornea were abraded and cross-linked with the photosensitizer riboflavin and UVA (370 nm, 3 mW/cm(2)) for 30 min. Optical coherence tomography pachymetry measurements of the central cornea were performed at various time intervals. RESULTS: Corneal thickness was reduced by 90.33 +/- 17.04 microm on average 3 days after cross-linking and by 93.67 +/- 14.22 microm after 8 months. The bullous changes of the epithelium were markedly improved, resulting in loss of pain and discomfort. Visual acuity was significantly improved in the case without prior stromal scarring. CONCLUSIONS: Cross-linking might become another useful tool in the treatment of bullous keratopathy. It is primarily suited for patients with pain symptoms, restricted visual prognosis or to extend the time interval for an upcoming corneal transplantation.

Hydration behavior of porcine cornea crosslinked with riboflavin and ultraviolet A.

PURPOSE: To examine the influence of a new crosslinking treatment on corneal swelling properties that correlate with the degree of crosslinking. SETTING: Department of Ophthalmology, Vivantes-Klinikum Neukölln, Berlin, Germany. METHODS: Twenty freshly enucleated porcine eyes were crosslinked by applying the photosensitizer riboflavin and ultraviolet-A (UVA) light (370 nm, 3 mW/cm2) for 30 minutes. After the eyes were treated and incubated for 24 hours in a moist chamber, 15 eyes were examined by biomicroscopy and optical coherence tomography (OCT); 5 eyes were examined by light microscopy. Five control eyes were included. RESULTS: Using light microscopy, a characteristic swelling pattern with 3 zones was identified in the crosslinked porcine cornea: an anterior intensely crosslinked zone of 242 microm, an intermediate partially crosslinked zone of 238 microm (hydration factor 2.2), and a noncrosslinked posterior zone of 1355 microm (hydration factor 2.7). A condensed OCT signal was demonstrated in the treated portion of the anterior stroma to a depth of 520 microm with a pronounced line at 540 microm, correlating with the combined anterior and intermediate layers after hydration in the histological analysis. In the nonhydrated state of the crosslinked cornea, the anterior zone was deduced to be 242 microm; the intermediate zone, 109 microm; and the posterior zone, 501 microm. Therefore, the maximum depth of the crosslinking effect was 351 microm. CONCLUSIONS: Collagen crosslinking using riboflavin and UVA led to a significant change in the swelling behavior of the anterior stroma, confirming prior findings that the crosslinking effect is strongest in the anterior half of the stroma. Crosslinked cornea did not induce a specific signal on OCT, and OCT is therefore not suited for clinical controls of the crosslinking effect.

Online optical coherence pachymetry to evaluate intraoperative ablation parameters in LASIK.

PURPOSE: The ablation of corneal tissue with the excimer laser can be variable and can lead to miscorrections. The purpose of this study was to evaluate intraoperative ablation parameters during laser-assisted in-situ keratomileusis (LASIK) with online optical coherence pachymetry (OCP). METHODS: In a prospective, nonrandomized, comparative clinical study, the ablation parameters were continuously assessed intraoperatively with online OCP (Heidelberg Engineering, Lübeck, Germany) in 45 myopic and 10 hyperopic LASIK treatments. The central intraoperative ablation values were compared with the calculated values of the excimer laser (ESIRIS, Schwind, Germany) and the postoperative refraction. The ablation process and the ablation rate in mum per layer, time, and dioptric correction were evaluated in myopic corrections. RESULTS: In myopic LASIK treatments, a linear ablation process was measured with a mean correlation coefficient of -0.968 +/- 0.04. The intraoperative ablation rate was, on average, 0.59 +/- 0.17 microm per layer, 1.45 +/- 0.48 microm per second, and 24.63 +/- 7.81 microm per corrected diopter. These values were 28.7% to 29.6% higher (P < 0.001) than the calculated values. There was a significant correlation (P < 0.001) for the ablation rate per layer (r = 0.823), per second (r = 0.869), and corrected diopter (r = 0.892), but no correlation (r = 0.21, P = 0.239) between the measured linear ablation process and the postoperative refraction. During hyperopic LASIK treatments, without ablation of the corneal center, there was a significant decrease (P = 0.005) of the stromal thickness by 18.34 +/- 14.13 microm, which corresponded to a mean corneal dehydration rate of 0.27 microm per second. CONCLUSIONS: Online OCP allowed a clinical evaluation of intraoperative ablation parameters in LASIK. Further studies are needed to assess a possible active control of the excimer laser ablation from these continuous values, which could possibly improve current ablation nomograms.

Continuous measurement of corneal dehydration with online optical coherence pachymetry.

PURPOSE: Online optical coherence pachymetry (online OCP) allows continuous central corneal thickness measurements over time. In this study, the effect of dehydration on corneal tissue was investigated with online OCP. METHODS: Twelve eyes of 11 patients were examined with online OCP, and the central corneal thickness was registered over 5 minutes after insertion of an eyelid speculum. RESULTS: Online OCP measurements revealed no decrease in reproducibility after 5 minutes of dehydration. The initial mean central corneal thickness was 538 +/- 48 microm. After 5 minutes the central corneal thickness decreased to 483 +/- 43 microm (P = 0.001). This corresponded to a mean corneal thinning of 55 +/- 4 microm (10.2%) at a rate of 0.19 microm/s. CONCLUSIONS: Online OCP was suitable for continuous measurements of corneal changes caused by dehydration. These dehydration effects should be particularly considered in refractive corneal surgery.

Experimental evaluation of online optical coherence pachymetry for corneal refractive surgery.

PURPOSE: Online optical coherence pachymetry (OCP) allows to monitor central changes of the corneal cross section intraoperatively. In this experimental evaluation the validity of the optical measurements for corneal refractive surgery was assessed. METHODS: Online OCP based on low-coherence interferometry with a wavelength of 1310 nm and a measurement frequency of 74 Hz was directly integrated in a clinical excimer laser. In 16 patients the central corneal thickness was measured with online OCP and ultrasound pachymetry (US). Furthermore, the ablation characteristics were assessed in corneoscleral discs unsuitable for transplantation (n=12) and PMMA samples (n=18). RESULTS: Online OCP was possible in all patients and materials studied. The mean central corneal thickness was 537+/-31 microm (OCP) and 546+/-33 microm (US). The corneal reproducibility was +/-4.3 microm (coefficient of variation [CV] 0.8%) with online OCP and +/-3.7 microm (CV 0.68%) with US. The reproducibility in PMMA samples was +/-1.0 microm (CV 0.16%). There was a significant correlation between online OCP and US measurements (r=0.93, P<0.001). The mean difference was 9.1 microm or 1.69% (P=0.01), and the limits of agreement (95% CI) ranged from -15 microm to 33 microm. There was a significant linear relationship (r=0,95; P<0.001) between the calculated and the optically determined ablation depth with online OCP. Also ablation depth measurements in PMMA correlated positively with spectrophotometric values (r=0.98; P<0.001). CONCLUSION: In this experimental evaluation, online OCP revealed to be a precise and reproducible method to assess the central corneal thickness and its changes intraoperatively. This could be important to monitor incisional and excimer laser-based corneal refractive procedures, such as PRK or LASIK.

Imaging scleral expansion bands for presbyopia with optical coherence tomography.

A 57-year-old woman was treated for mild presbyopia with implantation of scleral expansion bands (SEB). Although near vision was temporarily restored, the effect dissipated after 1 year. Slitlamp-adapted optical coherence tomography (OCT) at 1310 nm allowed precise cross-sectional visualization of the hyporeflective intrascleral segments. The OCT method provided precise images of the segment depth and thickness, the scleral thickness at the scleral spur, the anterior chamber angle, and the angle-opening distance. Intrascleral tilting of 1 segment was seen; this required removal of the SEB because of marked foreign-body sensation. Noncontact, slitlamp-adapted OCT can be used to evaluate scleral changes after SEB implantation.