Diffusion of the human retina and quality of the optics of the eye on the fovea and the peripheral retina

The linespread profile after double passage through the eye has been measured previously. We show that one cannot separate the contributions of the optics of the eye and of the retina to image degradation with this last method. We present here a new method which allows just such a separation. We have measured the modulation transfer function of the optics of the eye in the visual axis and oblique axes, and a function which characterizes light scattering in different portions of the living retina.     

Tonometry and the Elasticity of the Eye

This paper deals with the behaviour of the eye as an elastic body. An elastic body is one which tends to completely recover its original form following deformation.     

Tonometry and the Elasticity of the Eye

This paper deals with the behaviour of the eye as an elastic body. An elastic body is one which tends to completely recover its original form following deformation.     

A contribution to the histological and topographical anatomy of the aponeurosis of the levator palpebrae superioris and of the tarsal muscle in the normal lid and in blepharoptosis

Eight normal upper lids were examinated histologically with special regard to the aponeurosis of the levator and of the tarsal muscle (Müller's). The aponeurosis originates from the levator muscle within the orbit (behind the septum orbitale) and inserts at the upper anterior surface of the tarsal plate. The tarsal muscle originates from the levator muscle and inserts at the upper tarsal border. It is a smooth muscle containing many small blood vessels. Fifty-six specimens of tissue resected in operations for blepharoptosis were examined histologically. They consist of parts of the tarsal muscle and of the aponeurosis of the levator and of fat tissue without pathological changes.     

The influence of chronic diabetes mellitus on the thickness and the shape of the anterior and posterior surface of the cornea

PURPOSE: To determine the influence of diabetes mellitus (DM) type 1 and type 2 on the thickness, radius of curvature, power, and asphericity of the cornea. METHODS: In this observational cross-sectional study, 102 patients with DM type 1, 101 patients with DM type 2, and 69 healthy subjects were measured by means of Scheimpflug imaging to determine central corneal thickness and the radius and asphericity of the anterior and posterior corneal surfaces. Corneal power was calculated from these parameters. Several systemic parameters (eg, duration of diabetes, glycated hemoglobin, blood glucose levels, and type of medication) and ocular comorbidity (eg, stage of retinopathy) were recorded. RESULTS: Patients with DM type 1 and 2 had significantly smaller posterior corneal radii (P < 0.05) than those of healthy subjects (men: 6.49/6.48/6.64 mm; women: 6.36/6.30/6.49 mm). As a result, the optical power of the posterior corneal surface of the patients with diabetes differed from that of the healthy subjects (P < 0.01; men: DM, -6.2 D; healthy, -6.0 D; women: DM, -6.3 D; healthy, -6.2 D). However, corneal thickness, anterior radius and asphericity, and overall corneal power did not differ significantly between the groups. Furthermore, none of the systemic factors or ocular comorbidity had any influence on the corneal thickness or shape. CONCLUSIONS: DM affects the posterior corneal radius, resulting in a small change in posterior corneal power. However, chronic DM does not seem to significantly influence the overall corneal power.     

Isolation and characterization of the crystallins of the normal and cataractous canine lens

The lens crystallins were analyzed in normal dogs and Miniature offSchnauzer dogs with congenital cataract formation. There was an increase in the relative proportions of alpha and beta L-crystallin and a decrease in the beta H and gamma-crystallin with increasing age in the noncataractous lens. These trends were advanced in the age-matched cataractous lenses. "Advanced aging" trends were also noted in various polypeptide components of beta-crystallin. Specifically, the appearance of a 29K band as well as a reversal of the 26K to 27.6K ratio occurred at an earlier age in the cataractous lens than in the clear lens. Three subunits of approximately 19K, 20K, and 21.5K were present on SDS-PAGE for alpha-crystallin from the cataractous lens as opposed to only two of 19K and 21.5K from the clear lens. However, if the protein was not heated following resolubilization in buffer containing 2% SDS and 5% 2-mercaptoethanol, only two subunits of 20K and 21.5K were evident in both clear and cataractous lenses. The electrophoretic behavior observed for both alpha and gamma-crystallins did not appear to be age related.     

Relationship between vitrectomy and the morphology and function of the retina

Pathological processes in the vitreous will be reflected in the morphology and function of the retina, and these processes can originate from sources outside the vitreous. The purpose of vitreous surgery is to remove the qualitatively and/or morphologically diseased vitreous. Successful vitrectomy will be manifested by an improvement in the structure and/or function of the retina. We have evaluated the morphology of the vitreoretinal interface, and the function of the retina before and after vitreous surgery. Plasmin-assisted vitrectomy was used in some cases to remove the diseased vitreous more efficiently and less invasively. The effect of this procedure was assessed by examining the morphology and function of the retina. First, the relationship between the qualitative and structural abnormality of the vitreous in macular diseases was studied. In aphakic/pseudophakic eyes with cystoid macular edema, there was a depression of retinal function over the entire retina which may have been caused by chemical mediators released into the vitreous. These mediators may have been produced by inflammation in the anterior segment of the eye. In eyes with an idiopathic macular hole, optical coherence tomographic (OCT) images suggested that the progression of the macular hole might depend on a balance between foveal adhesion and the posterior vitreous. Second, the efficacy, surgical damage, and limitations of vitreous surgery were investigated. The recovery of macular function was assessed by focal macular electroretinograms (FMERGs) after vitrectomy for epiretinal membrane, choroidal neovascularization, and diabetic macular edema. The concurrent examination by optical coherence tomography (OCT) suggested that a decrease in retinal thickness contributed to the functional recovery. Macular functional recovery was delayed and limited after macular translocation, diabetic macular edema, and internal limiting membrane peeling. Third, we studied the effect of plasmin-assisted vitrectomy on the retina. The plasmin was used to remove the vitreous more completely and less invasively. In rabbits, ERG, OCT, and histological examinations demonstrated that the use of commercially-available plasmin at a concentration used on human patients resulted in temporary adverse effects on the retina. For human patients, we purified the plasmin from the patients' serum at the Nagoya University Hospital and the activity was about the same as in previous reports. The purified plasmin was approved by our hospital's institutional review board, and written informed consent was obtained from each patient. Patients with macular edema, idiopathic macular hole, and epiretinal membrane without posterior detachment underwent plasmin-assisted vitrectomy and were evaluated morphologically and electrophysiologically. The efficacy of the plasmin in separating the vitreo-retinal interface was demonstrated by an occasional spontaneous posterior vitreous detachment with or without core vitrectomy, and the presence of less vitreous cortex attached to the internal limiting membrane that was removed during vitrectomy. This was the first histological demonstration of the effectiveness of plasmin in the living eye. Full-field ERGs before and after surgery demonstrated clear evidence that no alteration of retinal functional had occurred, although we did detect a possible osmotic effect by an increase in OCT-determined retinal thickness by the high-molecular weight autologous plasmin. In future studies, the proper concentration and reaction time for each condition of the vitreous should be determined. In conclusion, the pathophysiology of the vitreous should reflect the retinal function. The recovery of the structure of the retina is important for the recovery of retinal function. This should always be the primary goal of surgeons who perform quality surgery.     

Topographic anatomy of the eyelids, and the effects of sex and age

AIMS: To describe the effects of sex and age on eyeball, eyelid, and eyebrow position. METHODS: A cross sectional cohort study was performed in which both eyes of 320 normal subjects aged between 10 and 89 years were included. Of each 10 year age cohort, there were 20 men and 20 women. Frontal, as well as lateral, slides were taken of both eyes. On projected slides, a reference line through the medial canthi and vertical lines through the pupil centre and the lateral canthus were constructed. Using these lines, we measured the size of the horizontal eyelid fissure, the distance from the reference line to the pupil centre and to the lateral canthus, the distance between the pupil centre and the upper and lower eyelid margin, and the distance between the upper eyelid margin and the skin fold and eyebrow. On lateral slides, the distance between the lateral canthus and the anterior corneal surface was measured. RESULTS: Between the ages of approximately 12 and 25 years, the horizontal eyelid fissure lengthened 3 mm, while the position of other eyelid structures remained virtually unchanged. Between the average ages of 35 and 85 years, the horizontal eyelid fissure gradually shortened again by about 2.5 mm. Meanwhile, the distance between the lateral canthal angle and the anterior corneal surface decreased almost 1.5 mm. Aging caused an increase of the distance between the pupil centre and the lower eyelid of about 1 mm in men, and 0.5 mm in women. Aging also caused a higher skin crease and raised eyebrows in men and women, but it did not affect the position of the pupil centre and the lateral canthus. Men showed an 0.7 mm larger horizontal eyelid fissure than women. In women, however, the eyebrows were situated about 2.5 mm higher than in men. CONCLUSION: Aging mainly affects the size of the horizontal eyelid fissure, which lengthens by about 10% between the ages of 12 and 25, and shortens by almost the same amount between middle age and old age. Aging causes sagging of the lower eyelid, especially in men, and a higher skin fold and eyebrow position in both sexes. Aging does not affect the position of the eyeball proper, or of the lateral canthus.