Intrinsically photosensitive (melanopsin) retinal ganglion cell function in glaucoma.

PURPOSE: To determine whether glaucoma alters intrinsically photosensitive retinal ganglion cell (ipRGC) function. METHODS: Forty-one patients (25 with glaucoma and 16 healthy age-matched control participants) were tested. Intrinsically photosensitive retinal ganglion cell function was directly measured by the sustained, postillumination pupil response (PIPR). Forty-one eyes of 41 participants were tested with 7°, 10-second, short-wavelength (488 nm; bluish) and long-wavelength (610 nm; reddish) stimuli (14.2 log photons · cm(-2) · s(-1)) presented to the right eye in Maxwellian view, and the consensual pupil response of the left eye was measured by infrared pupillometry. The difference between PIPR amplitude (percentage baseline pupil diameter), net PIPR (percentage change) and kinetics (time in mm · s(-1) to the PIPR plateau) for the blue and red stimuli in patients with early and advanced (moderate/severe) glaucoma was compared to that in age-matched control participants. RESULTS: The blue PIPR was significantly smaller between normal participants and patients with advanced glaucoma, as well as between those with early and those with advanced glaucoma (P < 0.05). The kinetics of the red and blue PIPRs were not significantly different between any groups. Normal age-matched participants and patients with early-stage glaucoma were not significantly different on any parameter, and neither was the normal and glaucoma group (advanced and early combined). CONCLUSIONS: Persons with moderate and severe glaucoma have a dysfunctional ipRGC-mediated PIPR. Intrinsically photosensitive retinal ganglion cell function measured directly with the PIPR may become a clinical indicator of progressive changes in glaucoma.

Surgical smoke management for minimally invasive (micro)endoscopy: an experimental study.

BACKGROUND: The aim of this study was to investigate the use of surgical smoke-producing procedures such as laser ablation or electrosurgery in minimally invasive microendoscopic procedures. This study proposes a technical solution to efficiently remove surgical smoke from very small endoscopic cavities using microports as small as 20 G (0.9 mm) in diameter. METHODS: The experimental laboratory study used small, rigid, transparent plastic cavity models connected with tubes and pressure sensors to establish an endoscopic in vitro laboratory model. A Kalium-Titanyl-Phosphate (KTP) laser with a 0.5-mm fiber optic probe was used to produce smoke from bovine scleral tissue in the cavity. Endoscopic gas insufflation into the model was generated by pressurized air and a microvalve. A laboratory vacuum pump provided smoke and gas suction via a microvalve. A self-built control and steering system was utilized to control intracavital pressure during experimental insufflation and suction. RESULTS: Problems related to smoke-generating processes, such as laser vaporization or electrocautery, in small closed cavities were first analyzed. A theoretical and mechatronic laboratory model was established and tested. Intracavital pressure and gas flow were measured first without and then with smoke generation. A new construction design for the suction tube was proposed due to rapid obstruction by smoke particles. CONCLUSIONS: Surgical smoke evacuation from endoscopic cavities that are as small as 2 cm in diameter via minimally invasive ports as small as 20 G (0.9 mm) in diameter may be safe and efficient if sufficient gas exchange is provided during smoke generation by laser or electrosurgical instruments. However, maintaining a low and constant pressure in the cavity during gas exchange and adopting a special construction design for the suction tube are essential to provide an excellent view during the surgical maneuver and to minimize potential toxic side effects of the smoke.

Analysis of three pigment epithelium-derived factor gene polymorphisms in patients with exudative age-related macular degeneration.

PURPOSE: Exudative age-related macular degeneration (exudative AMD) is a common vision-threatening disease, with both environmental and genetic factors contributing to its development. Recently, homozygosity for the 72Met variant of the pigment epithelium-derived factor (PEDF) Met72Thr gene polymorphism (rs1136287) was identified as a novel risk factor for exudative AMD in Chinese patients from Taiwan. The role of this polymorphism, however, has not yet been determined in a white European population. In addition, two other PEDF gene polymorphisms, -5736T>C (rs12150053) and -5304C>T (rs12948385), have been associated with increased risk of diabetic retinopathy, but have not yet been studied among patients with exudative AMD. The purpose of the present study was thus to investigate a hypothesized association between these PEDF polymorphisms and the presence of exudative AMD in a white European population. METHODS: The present case-control study comprised 269 patients with exudative AMD and 155 control subjects. Genotypes of the PEDF polymorphisms were determined by 5'-exonuclease assays (TaqMan). RESULTS: PEDF genotype and allele frequencies were not significantly different between AMD patients and control subjects. The two promoter polymorphisms, -5736T>C (rs12150053) and -5304C>T (rs12948385), were in complete association. Presence of the homozygous PEDF 72 Met/Met genotype was associated with a nonsignificant odds ratio of 1.00 (95% confidence interval: 0.67-1.49, p=0.99). Similarly, presence of the homozygous PEDF -5736 TT genotype or -5304 CC genotype was associated with a nonsignificant odds ratio of 0.99 (95% confidence interval: 0.56 - 1.75, p=0.97). Both promoter polymorphisms were in linkage disequilibrium with the Met72Thr (rs1136287) polymorphism (D'=0.83) and formed three common and one rare haplotype. Haplotype frequencies were similar between AMD patients and control subjects (p>0.05). CONCLUSIONS: Our data suggest that none of the investigated PEDF polymorphisms is likely a major risk factor for exudative AMD in a white European population.

Lymph node metastases arising from uveal melanoma.

Since the eye lacks lymphatic vessels, uveal melanomas primarily metastasize hematogenously. Here we report the case of a patient with ciliary body ring melanoma who developed lymph node metastases after a fistulating glaucoma operation. A 40-year-old female Caucasian patient presented with unilateral pigment dispersion. Pigment dispersion glaucoma was diagnosed and since the intraocular pressure could not be managed with topical medication, transscleral cyclophotocoagulation and two trabeculectomies had to be performed. Due to enlargement of the pigmented iris mass and cell deposits in the chamber angle, a ciliary body ring melanoma was presumed and the eye enucleated. Histology confirmed the diagnosis of "ciliary body ring melanoma". Six months after enucleation the patient presented multiple metastases including ipsilateral preauricular and submandibular lymph node metastases. The patient died two months later. Lymph node metastases arising from ciliary body melanomas are very rare. Tumor seeding through the trabeculectomy site into the bleb and then via conjunctival lymphatic vessels might be the crucial factor for this pathway of metastases. Therefore, in cases of unilateral pigment dispersion, malignancy should be excluded before fistulating operations are performed.

Evaluation of a KTP (potassium-titanyl-phosphate) 532 nm laser for endovaporization of choroidal melanomas.

BACKGROUND AND OBJECTIVES: The purpose of this in vitro study is to evaluate the use of the KTP (potassium-titanyl-phosphate) 532 nm laser for future use in endovaporization of large choroidal melanomas. STUDY DESIGN/MATERIALS AND METHODS: A KTP 532 nm green laser coupled to a 0.3 mm fiberoptic probe was used to perform in vitro studies on human cadaver eyes and on one enucleated melanoma eye. The specimens were examined by histological staining (Masson-Trichrome) and scanning electron microscopy (SEM). RESULTS: Histological analysis of sclera, choroid, retina, and melanoma revealed different zones of collateral thermal tissue damage. These zones were analyzed quantitatively. We determined the best suitable laser parameters and the time for sclera penetration. CONCLUSIONS: The KTP-laser showed good potential in intraocular vaporization of choroidal melanomas. However, great differences in laser absorption between sclera and melanoma can cause significant complications such as perforation.