Erik Krogh

Natural course in fellow eyes of patients with unilateral age-related exudative maculopathy. A fluorescein angiographic 4-year follow-up of 45 patients.

Abstract A prospective fluorescein angiographic study of 45 patients with unilateral age‐related exudative maculopathy revealed at the 4‐year follow‐up that 14 (31%) had developed neovascular membranes in the fellow eyes. Age, drusen size and confluence, as well as pigmentary changes of these 14 were compared with the corresponding characteristics of the 31 eyes that remained non‐exudative (atrophic). No significant differences were found. Among the 14 eyes that developed exudative maculopathy, visual acuity (Snellen) deteriorated 3–4 steps in 6 eyes (43%), 5–6 steps in 4 eyes (28.5%), and 7–8 steps or more in 4 eyes (28.5%). Among the 31 eyes that remained non‐exudative, visual acuity was unchanged in 20 eyes (64%), deteriorated 1–2 steps in 7 eyes (23%), 3–4 steps in 3 eyes (10%), and 5–6 steps in 1 eye (3%). Social blindness (6/60 or less in the better eye) was found among 79% of the patients who had developed exudative maculopathy, whereas the figure was 19% among patients who still had atrophic macular degeneration.

Normal values in clinical electrooculography. 1. Material, method, methodological investigations and distribution of the potential and time parameters.

For the evaluation of normal EOG potential and time parameters a case series (142 eyes) is presented. An EOG technique aiming at the largest possible amplitude between the dark trough and the light peak is described. It is shown that the light‐induced response following a 20 min period of adaptation to a very low degree of illumination (about 1/10 lx, allowing a rough orientation on the displayed trace) does not differ from that produced after 20 min of total darkness. Also, the independence of the pupillary area for the light‐induced response is demonstrated, which means that the light stimulus employed (2500–4000 lx) is supramaximal. Furthermore, the good quality of the gaze fixation in the actual test situation with respect to the recording of equidistant saccades is proven. A DC amplification of the signal is used, which secures independency of inter‐ and intra‐individual differences in the saccadic velocity and makes possible accurate measurements of deflections disfigured by correcting movements. The following EOG parameters are recorded: A base value after 10 min of preadaptation with the light stimulus, the dark trough and the light peak potentials. Also the periods between the beginning of the dark adaptation and the dark trough and between the dark trough and the light peak are noted. The frequency distribution and the general level of the various parameters are discussed in the light of comparable figures of previous publications.

Normal values in clinical electrooculography. II. Analysis of potential and time parameters and their relation to other variables.

The following EOG potential and time parameters from 72 normal subjects were analysed: base value B, dark trough D, light peak L, light induced potential rise L‐D, interval between beginning of dark adaptation and occurrence of dark through d and interval between dark trough and light peak I. Their relations to sex, age, pupillary diameter, degree of iris pigmentation, refractive error, axial length, corneal curvature and diameter, ocular protrusion and interpupillary distance were assessed. Right eye and left eye samples of the EOG parameters were congruent, although individual differences were sometimes appreciable. The levels of B and D were higher in the female half of the sample. A positive correlation existed between age and D level. L‐D was negatively correlated to the degree of refractive error and positively correlated to the ocular protrusion. A positive correlation was found between d and the four potential parameters, and there was a positive correlation between age and I. Practical consequences of the statistical analysis relating to the interpretation oi such EOG data are discussed.

Visual evoked response and alcohol intoxication

Twelve eye healthy test persons were followed for 2 h after alcohol intake by frequent recordings of visually evoked pattern responses (VERs) and simultaneous determinations of the blood alcohol concentrations. VERs were recorded with a stimulus of 14′ and 110′ check size, and for both check sizes steady state (15 shifts per sec) and transient responses (2 shifts per sec) were analyzed. In the transient responses we found a general increase in latencies after alcohol intake, but only in one stimulus modality (2 shifts per sec, 14′ check size) was the deviation statistically significant. The steady state responses showed a large pre‐alcoholic variability both in amplitudes and in lantencies. No change was descernible after alcohol intake. No correlation was found between the various levels of alcohol concentration and any of the VER parameters. The minor changes of the VER found in this study using a patterned stimulus are discussed and compared to the findings in earlier studies using a flash as well as a patterned stimulus.

Normal values in clinical electrooculography. IV. Analysis of two dimensionless EOG parameters and their relation to other variables.

Two EOG parameters ‐ The Arden ratio (A) and an expression devised by Gliem (G) ‐ from a sample of normal human subjects are studied. Their relations to the EOG potential and time parameters and to sex, age, pupillary diameter, degree of iris pigmentation, refractive error and axial length, ocular protrusion and interpupillary distance were assessed. Right eye and left eye distributions were congruent, although individual differences were sometimes appreciable, especially in the case of G. The two ratios were positively correlated and both showed a negative correlation to the interval between the dark trough and the light peak. Correlations to the EOG potential parameters, especially the light induced potential rise of the dark adapted eye, were also established.

Normal values in clinical electrooculography. III. Numerical evaluation of two dimensionless EOG parameters.

The distribution of the Arden ratio (A) and another dimensionless EOG quantity (G) devised by Gliem (1971) in a sample of normal human subjects are presented. The minimum, median and maximum values for A are 148–241‐449 and for G 34–88‐167. A demonstrates a smaller degree of dispersion than G, the latter resembling in this respect the EOG potential parameters of the same sample. The average accumulation of errors due to inaccurate assessment of the included potential figures is almost equal in the functions of A and G. Divergencies between the figures from the present and earlier investigations are discussed together with the general advantage of dimensionless EOG parameters. It is concluded that the present investigation has not demonstrated the need to replace or supplement the Arden ratio by the Gliem quantity.

PROGNOSTIC PARAMETERS IN PARS PLANA VITRECTOMY

Based on a period of introduction with the vitrectomy technic the visual acuity results in 143 consecutive cases performed between 1976 and 1980 are related to the anamnestic information, the pre‐, per‐ and post‐operative findings. In this introductional period the patients referred had longstanding retinovitreal changes, and, because of lack of prognostic parameters, all patients were offered surgery regardless of the observed pathology. All vitrectomies were carried out with the Klöti macrostripper and diathermy unit, without any additional intrumentation. From the results of these early cases, we have changed our surgical method to a three‐port entrance with a separate infusion canula, a separate fiberoptic illumination and an interchange between vitrector, automatic scissors, hook, stilleto, vacuo needle, forceps and intra‐vitreous photocoagulation through a third port. Diabetics should be offered vitrectomy if vitreous haemorrhages last for more than 3 months. Vitrectomy is considered useless or contraindicated in diabetics with lack of light perception or light projection, neovascular glaucoma, extinguished visual evoked potential. Only an improvement in the peripheral vision can be expected in diabetics with macular detachment. In rhegmatogenous detachment cases with intravitreal traction, vitreous operations should be performed only where intraretinal or retroretinal changes do not prevent mobilization or unfolding of the retina. Traumatic vitreoretinal disorders should be operated upon early

HISTOPATHOLOGICAL FINDINGS IN FAILED HUMAN EPIKERATOPHAKIA LENTICULES

Abstract. Six human epikeratophakia lenticules were removed 1 to 23 months after refractive keratoplasty for aphakia (n = 2) and myopia (n = 4). The myopic group included one epi‐lenticule treated with ArF‐excimer laser for hyperopia. Reasons for removal were epithelial defect (n = 4), edema of host cornea (n = 1), and overcorrection (n = 1). The epi‐lenticule stroma showed centrally a regular fibrillar structure with a low keratocyte density. Electron microscopy (n = 1) revealed preserved cytoplasmic organelles and nuclear appearance. Mononuclear cells were absent. Polysaccharide was demonstrated in the stroma. Bowmans layer was normal without breaks. The epithelium had variable thickness. In the peripheral wound region stromal and epithelial irregularities were evident.

VER IN INTRAOCULAR HYPERTENSION: Short Communication

Transient and steady state VERs before and after artificial IOP elevation were recorded from 16 eyes (9 persons) with untreated intraocular hypertension observed for several years without signs of functional loss or optic disc changes. Four eyes (two patients) demonstrated a pathological transient VER amplitude drop after pressure increase. One eye with an ophthalmoscopically atypical disc presented a grossly deformed transient VER at the habitual pressure level; the fellow eye was lost from trauma. Another eye presented an abnormal VER pattern and showed as yet normal function and ophthalmoscopy, the fellow eye had developed open angle glaucoma and showed identical VER changes. The prognostic and diagnostic implications are briefly discussed.

EOG CHANGES IN PHOTOCOAGULATION OF DIABETIC RETINOPATHY

Ten patients with bilateral, proliferative diabetic retinopathy and normal visual acuity in both eyes received photocoagulation in one eye by argon‐laser. Electrooculography (EOG) was performed on the day before, the day after, and 6—8 weeks after the photocoagulation. The pre‐treatment Arden coefficient was reduced in all patients. After the photocoagulation an immediate reduction in the Arden coefficient occurred remaining unchanged for 6—8 weeks after treatment. The untreated eye showed an unchanged Arden coefficient during the observation period, not differing from the EOG in the treated eye before the photocoagulation.