Hexagonal keratotomy for intraocular lens miscalculation.

As the result of miscalculation of the intraocular lens before cataract surgery, hyperopia and anisometropia developed in a 67-year-old woman. Hexagonal keratotomy performed 7 years later under topical anesthesia with a 5-mm marker resulted in a myopic shift of 4.37 dioptres and an uncorrected visual acuity of 20/25.

Subjective and objective findings after radial keratotomy.

Monocular diplopia secondary to radial keratotomy was investigated in a 42-year-old ophthalmologist. Under certain conditions, the patient observed a ghost image, loss of contrast, and variability in the subjective refraction. The objective findings were scissoring of the retinoscopic reflex, a prominent iron line, and localized flattening of the cornea.

Why are refractive surgeons still wearing glasses?

A 38-year-old ophthalmologist describes his thoughts and perceptions before, during, and for 12 months after bilateral radial keratotomy. Three kinds of visual fluctuations were experienced. Adaptation to monovision was good.

Diurnal cycle of refraction after radial keratotomy.

A single patient was refracted 1000 times at all hours of the day in the year after bilateral radial keratotomy (RK). Preoperatively, there was practically no diurnal variation of refraction. Postoperatively, the refraction showed a myopic shift of several diopters from early morning to late evening. Transient hyperopia was superimposed on this diurnal cycle of refraction, peaking two weeks postoperatively, and a smaller long-term hyperopic shift was evident 1 year postoperatively.

Simultaneous bilateral iris metastases from renal cell carcinoma.

A 60-year-old man experienced a sudden painless decrease in visual acuity in his right eye. An examination disclosed a 2.8-mm mass attached to the iris collarette in each eye. Investigation showed a 10-mm mass in the inferior pole of the left kidney. The iris nodules and the affected kidney were removed. Although the patient died of cerebral metastases three months after surgery, the iris masses did not recur, the patient's discomfort was minimal, and his visual acuity remained normal.

Discharge properties of pontine reticulospinal neurons during sleep-waking cycle.

1. Reticulospinal neurons were identified by antidromic invasion from spinal cord electrodes chronically implanted at C4 in cats. 2. Most of the neuronal population studied lay within the medial portion of the giant cell field from the anterior pontine and to the anterior medullary reticular formation (FTG). A few cells were found in the tegmental reticular nucleus (TRC) which has not previously been known to project to the spinal cord. 3. Extracellular action potentials from the neuronal somata of the identified neurons were recorded continuously throughout naturally occurring sleep-waking cycles. 4. The identified reticulospinal neurons shared three properties, suggesting a generator function in desynchronized sleep (D) (with previously recorded but unidentified FTG neurons): selectivity (or concentration of discharge in D); tonic latency (or firing rate increases beginning several minutes prior to D); and phasic latency (or firing rate increases occurring prior to eye movements within D). 5. The location, discharge properties, and spinal projections of FTG neurons are, thus, all consistent with the hypothesis that they may directly mediate some of the descending excitatory and inhibitory influences on spinal reflex pathways in desynchronized sleep.

Sleep cycle oscillation: reciprocal discharge by two brainstem neuronal groups.

During the sleep cycle in cats, neurons localized to the posterolateral pole of the nucleus locus coeruleus and the nucleus subcoeruleus undergo discharge rate changes that are the opposite of those of the pontine reticular giant cells. The inverse rate ratios and activity curves of these two interconnected populations are compatible with reciprocal interaction as a physiological basis of sleep cycle oscillation.