The Berkeley Contact Lens Extended Wear Study. Part II : Clinical results

OBJECTIVE: To describe the principal clinical outcomes associated with 12 months use of rigid gas-permeable (RGP) extended wear contact lenses and address two primary study questions: (1) does extended wear (EW) of high oxygen transmissibility (Dk/t) RGP lenses reduce the incidence of ocular complications, and (2) does the wearing of high-Dk/t lenses reduce the rate of failure to maintain 6-night RGPEW over 12 months? DESIGN: A randomized, concurrently controlled clinical trial. INTERVENTION: Subjects who adapted to EW with high Dk (oxygen permeability) RGP lenses were randomized to either high Dk or medium-Dk RGP lenses for 12 months of 6-night EW. MAIN OUTCOME MEASURES: Contact lens-associated keratopathies (CLAK), changes in refractive error and corneal curvature, and survival in EW. RESULTS: Two hundred one subjects were randomized to medium or high-Dk lenses for 12 months of EW. Sixty-two percent of the subjects in each group completed 12 months of EW; however, the probability of failure was significantly greater for the medium-Dk group. Although the risk of complications was similar for the two groups, the number of CLAK events that led to termination were 16 versus 5 for the medium-Dk and high-Dk groups, respectively. This suggests that the type of adverse response or the inability to reverse an adverse event was different for the group being exposed to the lower oxygen dose. CONCLUSIONS: The level of oxygen available to the cornea has a significant impact on maintaining successful RGP extended contact lens wear, but not on the initial onset of CLAK. The number of clinical events leading to termination was substantially higher for the medium Dk group, which suggests that corneal hypoxia is an important factor in the development of CLAK. Although overnight contact lens wear should be recommended with caution and carefully monitored for early detection of ocular complications, it appears that high-Dk RGP lenses can be a safe and effective treatment for correction of refractive error for most individuals who can adapt to EW.     

The ophthalmic wound of Philip II of Macedonia (360-336 BCE)

The aim of this report is to present the ophthalmic wound of King Philip II of Macedonia, father of Alexander the Great. From a series of ancient literary and historical sources, a number of archaeological finds, and the paleopathological remains in the supposed tomb of Philip in Vergina, it can be deduced that the king was seriously wounded in his right eye during the siege of Methoni. The renowned physician Critobulos undertook the removal of the arrow that had injured the eye and the postoperative follow-up. He was already experienced and belonged to the official medical family of Asclepiades of Cos Island. It seems that an ugly scar remained in the area of Philip's right eye, possibly causing him psychological problems.     

Retinoblastoma update--therapy (Part II)

The aim of this paper is to present updated data on the treatment of retinoblastoma. The authors describe current management based on the International Intraocular Retinoblastoma Classification (IIRC). They discuss the different methods of treatment, including chemoreduction, subconjunctival carboplatin, transpupillar thermotherapy, cryotherapy, laser photocoagulation, episcleral plaque radiotherapy, external-beem radiotherapy and enucleation.     

The different effects of fe(II)- and fe(III)-ions on the hyaluronic acid of the vitreous body (author's transl)]

Fe(II)-ions reduce the viscosity of a hyaluronic acid solution but do not form a precipitate. Fe(III)-ions only slightly lower the viscosity of hyaluronic acid solutions but cause a brown, water-insoluble iron-hyaluronic acid precipitate. After adding ascorbic acid--concentrate the pH-value as in vitreous body--to the reaction solution, Fe(III)-ions reduce the viscosity too. The iron-hyalurnic acid complex is also destroyed by ascorbate. Therefore, the ascorbate of the vitreous humor plays an important role in the generation of siderosis bulbi.     

Electroretinography in monitoring of glaucoma (II)

Pattern ERG represents an effective mean for ocular disease examination where the retinal ganglion cells are lost. Pattern ERG is required as an objective technique in the diagnosis and the tracking of the glaucomatous disease, allowing, with visual perimetry more specific identification of retinal lesions areas.