Alexander M. Eaton

Condensation on the Posterior Surface of Silicone Intraocular Lenses during Fluid—Air Exchange

PURPOSE Posterior chamber foldable silicone intraocular lenses (IOLs) are becoming increasingly prevalent in patients undergoing a pars plana vitrectomy with fluid-air exchange. The authors report an important limitation of foldable silicone IOLs during fluid-air exchanges in pars plana vitrectomies. METHODS The charts of 18 pseudophakic patients with foldable silicone IOLs who underwent vitrectomy with fluid-air exchange by the authors were reviewed. RESULTS There was a statistically significant difference in the occurrence of condensation during fluid-air exchange between the group of patients with a capsulotomy versus those that did not have a capsulotomy (P = 0.003). Condensation limiting the view of the retina occurred during fluid-air exchange in 11 of 11 of the patients with foldable silicone lenses and a capsulotomy. Attempts to remove the condensation with a soft-tipped aspiration cannula resulted in limited view of the retina for 1 to 2 minutes in 6 of 11 patients. Use of a thin film of silicone oil restored the view in one patient. In the presence of an intact posterior capsule, condensation did not occur on identical foldable silicone IOLs in seven of seven patients. CONCLUSION Recognition of the presence of a foldable silicone lens is important when an air-fluid exchange is anticipated. If a capsulotomy is present, the surgeon must be aware that condensation may limit the view of the retina severely during and after surgery. Intraoperatively, the view of the retina usually can be restored in short surgeries by wiping the posterior lens surface with a soft-tipped cannula, and in more complex surgeries by applying a thin film of silicone oil on the posterior surface of the lens.

Increased incidence of sterile endophthalmitis after intravitreal triamcinolone acetonide in spring 2006.

Purpose: To compare the incidence of sterile endophthalmitis after intravitreal triamcinolone acetonide injections during a 6 month period in 2006 to the same period in 2005 and determine the incidence after switching to intravitreal preservative-free triamcinolone acetonide. Methods: Retrospective multicenter interventional case series in which patients receiving intravitreal triamcinolone acetonide at three institutions from March 2005 to August 2005 and from March 2006 to August 2006 and intravitreal preservative-free triamcinolone acetonide from late summer 2006 through February 2007 were reviewed for the development of sterile endophthalmitis. Results: From March 2005 to August 2005, the rate of sterile endophthalmitis was 0% at all institutions. From March 2006 to August 2006, a statistically significant increase in sterile endophthalmitis was seen at all institutions with frequencies of 3.5% to 6.3% (P < 0.001). With transition to preservative-free triamcinolone acetonide, sterile endophthalmitis over the next 6 months decreased to 0% at two sites and to 2.5% (from 5.5%) at the third institution (P < 0.009). Conclusions: A statistically significant increase in the rate of sterile endophthalmitis after intravitreal triamcinolone acetonide was seen in a 6 month period in 2006 when compared with the same period in 2005. Transition to preservative-free triamcinolone acetonide produced a frequency of sterile endophthalmitis similar to 2005.

Assessment of Novel Guarded Needle to Increase Patient Comfort and Decrease Injection Time During Intravitreal Injection

BACKGROUND AND OBJECTIVE To determine whether a novel guarded 33-gauge injection device can make the intravitreal injection procedure faster and more comfortable for patients. PATIENTS AND METHODS Single-center, prospective, randomized interventional study. Seventy participants receiving bilateral injections on the same day had one eye injected with the 33-gauge injection device without a speculum and the other eye injected with a standard 30-gauge needle using a speculum. Length of time needed for the injection procedure was assessed, and subjects were asked to complete a questionnaire regarding their comfort level with each device during the injection procedure as well as immediately after, later that evening, and the next day. RESULTS Intravitreal injections using the 33-gauge injection device were significantly faster, but there was no significant difference in the incidence or levels of pain between the two needle types. CONCLUSION The 33-gauge injection device may offer advantages over a standard 30-gauge needle when performing an intravitreal injection.

Injection force comparison of the old and new dexamethasone implant insertion needles in porcine eyes and synthetic sclera.

BACKGROUND AND OBJECTIVE Determine whether the new dexamethasone intravitreal implant (Ozurdex; Allergan, Irvine, CA) injector needle design can reduce the force needed for insertion when compared to the original needle design. MATERIALS AND METHODS In vitro testing assessed the force required for insertion from five new-design and five old-design Ozurdex needles on a synthetic test medium and explanted porcine eyes. Maximum penetration force was measured in grams-force, while the total work of the needle was measured in joules. RESULTS The new design required 29% and 68% less overall work to perform an injection in the synthetic medium (P = .0002) and porcine eyes (P = .009), respectively. The maximum force required to insert the new needle was 25% and 61% that of the old needle in the synthetic medium (P = .001) and porcine eyes (P = .007), respectively. CONCLUSION The new needle design significantly reduces the force and work needed for insertion, which should improve physician control as well as patient safety and comfort.

Secondary Ocular Hypertension and the Risk of Glaucoma Surgery After Dexamethasone Intravitreal Implant in Routine Clinical Practice

BACKGROUND AND OBJECTIVES To determine the rate of ocular hypertension (OHT) after dexamethasone intravitreal implant in routine clinical practice and identify patient characteristics associated with a risk for glaucoma surgery. PATIENTS AND METHODS The charts of 260 eyes from 221 patients with diabetic macular edema, retinal vein occlusion, uveitis, and macular edema secondary to various causes treated with one or more dexamethasone implants were reviewed. Intraocular pressure (IOP), medications, and glaucoma interventions were collected before and after implantation. RESULTS The mean baseline IOP was 14.3 mm Hg ± 3.6 mm Hg, and after receiving dexamethasone implant(s), 26.2% and 7.7% of patients had IOP greater than 25 mm Hg and 35 mm Hg, respectively. There was evidence (P < .001) of an association between preexisting glaucoma or glaucoma suspect status (103 eyes) and need for glaucoma surgery, and 4.62% (12 eyes) required glaucoma surgery. CONCLUSIONS Secondary OHT induced by the dexamethasone implant can usually be controlled by medications, but the incidence of OHT requiring glaucoma surgery was high (4.62%) in our study relative to rates previously reported in the literature. All patients, especially those with preexisting glaucoma, should be advised of the possible need for glaucoma surgery prior to undergoing treatment with the dexamethasone implant. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:680-685.].

Central retinal artery occlusion on postoperative day one after vitreoretinal surgery

Purpose To report two cases of central retinal artery occlusion (CRAO) associated with vitreoretinal surgery. Observations Two patients underwent vitreoretinal surgery and were diagnosed with CRAO on postoperative day one. Both had received retrobulbar anesthetic blocks, followed by pars plana vitrectomy in one patient and scleral buckling in the other patient. Best-corrected visual acuity at last follow-up was 20/40 and 20/400. Conclusions/Importance CRAO is a rare but serious adverse event after vitreoretinal surgery. The causative mechanism is not known in these patients.

Improving Outcomes for Patients With Diabetic Macular Edema.

Diabetic macular edema (DME) is one of the most common causes of vision loss in patients who have diabetes, and all of these patients are at risk for developing DME. The onset is often painless, difficult to detect, and can occur at any stage of diabetes. Ideally, DME is preventable, but treatment must be considered when preventative methods fail. Although physicians have several different treatment options for patients with DME, some patients who receive treatment can respond poorly and may even lose vision. Until recently, laser photocoagulation was regarded as the standard of care for DME; however, pharmaceutical treatments are rapidly replacing this standard as the desire to maximize systemic treatment of DME increases. A panel of experts gathered during the 2015 annual meeting of the Association for Research in Vision and Ophthalmology for a roundtable discussion designed to focus on improving outcomes for patients with DME using pharmaceutical treatment, including the use of anti-VEGFs and corticosteroids, based on the most current research and clinical data.

Determination of oxygen saturation of the optic nerve head and overlying artery and vein using a snapshot multi-spectral imaging system

We have developed a snapshot optical imaging system capable of taking multiple images simultaneously and sending them to a CCD detector. Using an innovative lens array design, the beam obtained from the fundus camera is segmented into several different images passed through several different bandpass filters. Each bandpass filter defines a unique spectral region of imaging. The images are taken simultaneously into a large silicone chip with a dynamic range of 16 bits (highly sensitive) and are integrated with a single optical connection to a digital fundus camera. Our algorithm maps blood oxygen saturation of the retina using several wavelengths. These wavelengths are capable of approximating the whole hemoglobin spectrum and have been found from a previously developed hyperspectral algorithm. They include four isosbestic points (522, 548, 569, and 586 nm) and three oxygen-sensitive points (542, 560, and 586 nm) where the difference between fully oxygenated and deoxygenated blood is at a maximum. Using MatLab code, color maps of oxygen saturation are produced. The average value taken from all vein areas was 60.53%, assuming that the artery oxygen saturation value is 98%. Oxygen saturation of the tissue was 75.78%. Oxygen saturations of the temporal/inferior/nasal veins ranged from 61.86% to 63.37%; the superior vein was significantly lower (54.19%). Tissue oxygen saturations in different quadrants of the eye ranged from 74.17% to 76.74%. Our algorithm has been developed for measuring oxygen saturation of the retina clinically. This was done for one subject only; further work can extend the measurements to different pigments.

Preliminary results using a flexible endoscope for orbital surgery

A technique for visualizing the optic nerve, the short and long posterior ciliary arteries and nerves, the ophthalmic vein, and the rectus muscles using a flexible endoscope was developed in human cadavers. Previous reports of orbital endoscopy were limited to the use of a rigid endoscope. Potential applications for this new flexible endoscopic technique include the biopsy of orbital tumors, fenestration of the optic nerve sheath with mid-infrared lasers, photocoagulation of orbital tumors, and retrieval of foreign bodies or slipped muscles.