Long-term assessment of visual and refractive outcomes of laser in situ keratomileusis for hyperopia using the AMARIS® 750S Excimer laser.

PURPOSE: To evaluate the long-term efficacy and safety of hyperopic laser in situ keratomileusis (LASIK) using the AMARIS® 750S (Schwind, Eye-tech-solutions, GmbH) excimer laser. METHODS: The medical records of one hundred eleven eyes of 62 patients who underwent LASIK for hyperopia using the AMARIS® 750S excimer laser were reviewed retrospectively. Patients were divided into three groups based on preoperative spherical equivalent (SE) refraction: low hyperopia (less than +2.50 diopters [D]), moderate hyperopia (+2.75D to +4.00D), and high hyperopia (over +4.00D). Uncorrected and best corrected visual acuity (BCVA), long-term stability of refraction, and complications were evaluated. RESULTS: Of the entire sample, the mean preoperative SE was +3.64D±1.22D. The mean age was 37.4±11.2 years (20-59). The mean follow-up for all eyes was 51 months. At the last visit, the mean SE was +0.85D±0.34D (SD) in the low hyperopia group, +1.09D±0.43D in the moderate hyperopia group, and +1.63D±0.47D in the high hyperopia group. (+1.15D±0.49D overall). Preoperative uncorrected visual acuity (UCVA) was 0.52±0.34 logMAR and increased to 0.18±0.15 logMAR at 4 years follow-up (P<0.01). There was no statistically significant difference between preoperative and postoperative BCVA. The UCVA was 0.30 logMAR or better in 100% of eyes in the low hyperopia group, 93.7% in the moderate hyperopia group, and 69.9% in the high hyperopia group (%89.2 overall). CONCLUSIONS: LASIK is safe and effective for correcting hyperopia in the short term; however, the efficacy of the procedure is limited in the patients with high hyperopia and longer follow-up.

Retina dose as a predictor for visual acuity loss in 106Ru eye plaque brachytherapy of uveal melanomas.

BACKGROUND AND PURPOSE: To evaluate the retina dose as a risk factor associated with loss of visual acuity (VA) in 106Ru plaque brachytherapy. MATERIAL/METHODS: 45 patients receiving 106Ru plaques brachytherapy (median follow-up 29.5 months) were included in this study. An in-house developed treatment planning system with Monte Carlo based dose calculation was used to perform treatment planning and dose calculation. Risk factors associated with loss of VA were evaluated using the Cox proportional hazards models, Kaplan-Meier estimates and Pearson correlation coefficients. RESULTS: A significant correlation was found between VA loss and mean (r = 0.49, p = 0.001) and near maximum (r = 0.47, p = 0.001) retina dose D2% and tumor basal diameter (r = 0.50, p < 0.001). The Kaplan-Meier and Cox proportional hazards model yielded a significantly higher risk for VA loss (>0.3Snellen) for patients receiving a maximum dose of >500 Gy (p = 0.002). A Cox multivariate analysis including the macula dose (p = 0.237) and basal diameter (p = 0.791) showed that a high maximum retinal dose is the best risk factor (p = 0.013) for VA loss. CONCLUSION: The study showed that retina dose (D2% and Dmean) is a suitable predictor for VA loss.

Outcomes of proton therapy for the treatment of uveal metastases.

PURPOSE/OBJECTIVE(S): Radiation therapy can be used to treat uveal metastases with the goal of local control and improvement of quality of life. Proton therapy can be used to treat uveal tumors efficiently and with expectant minimization of normal tissue injury. Here, we report the use of proton beam therapy for the management of uveal metastases. METHODS AND MATERIALS: A retrospective chart review was made of all patients with uveal metastases treated at our institution with proton therapy between June 2002 and June 2012. Patient and tumor characteristics, fractionation and dose schemes, local control, and toxicities are reported. RESULTS: Ninety patients were identified. Of those, 13 were excluded because of missing information. We report on 77 patients with 99 affected eyes with available data. Patients were 68% female, and the most common primary tumor was breast carcinoma (49%). The median age at diagnosis of uveal metastasis was 57.9 years. Serous retinal detachment was seen in 38% of treated eyes. The median follow-up time was 7.7 months. The median dose delivered to either eye was 20 Gy(relative biological effectiveness [RBE]) in 2 fractions. Local control was 94%. The median survival after diagnosis of uveal metastases was 12.3 months (95% confidence interval, 7.7-16.8). Death in all cases was secondary to systemic disease. Radiation vasculopathy, measured decreased visual acuity, or both was observed in 50% of evaluable treated eyes. The actuarial rate of radiation vasculopathy, measured decreased visual acuity, or both was 46% at 6 months and 73% at 1 year. The 6 eyes with documented local failure were successfully salvaged with retreatment. CONCLUSIONS: Proton therapy is an effective and efficient means of treating uveal metastases. Acutely, the majority of patients experience minor adverse effects. For longer-term survivors, the risk of retinal injury with vision loss increases significantly over the first year.

Accurate estimation of dose distributions inside an eye irradiated with 106Ru plaques.

BACKGROUND: Irradiation of intraocular tumors requires dedicated techniques, such as brachytherapy with (106)Ru plaques. The currently available treatment planning system relies on the assumption that the eye is a homogeneous water sphere and on simplified radiation transport physics. However, accurate dose distributions and their assessment demand better models for both the eye and the physics. METHODS: The Monte Carlo code PENELOPE, conveniently adapted to simulate the beta decay of (106)Ru over (106)Rh into (106)Pd, was used to simulate radiation transport based on a computerized tomography scan of a patient's eye. A detailed geometrical description of two plaques (models CCA and CCB) from the manufacturer BEBIG was embedded in the computerized tomography scan. RESULTS: The simulations were firstly validated by comparison with experimental results in a water phantom. Dose maps were computed for three plaque locations on the eyeball. From these maps, isodose curves and cumulative dose-volume histograms in the eye and for the structures at risk were assessed. For example, it was observed that a 4-mm anterior displacement with respect to a posterior placement of a CCA plaque for treating a posterior tumor would reduce from 40 to 0% the volume of the optic disc receiving more than 80 Gy. Such a small difference in anatomical position leads to a change in the dose that is crucial for side effects, especially with respect to visual acuity. The radiation oncologist has to bring these large changes in absorbed dose in the structures at risk to the attention of the surgeon, especially when the plaque has to be positioned close to relevant tissues. CONCLUSION: The detailed geometry of an eye plaque in computerized and segmented tomography of a realistic patient phantom was simulated accurately. Dose-volume histograms for relevant anatomical structures of the eye and the orbit were obtained with unprecedented accuracy. This represents an important step toward an optimized brachytherapy treatment of ocular tumors.