Tetracaine toxicity.

Severe ocular complications developed in a patient after use of a topical anesthetic (tetracaine 0.5% ophthalmic ointment) over a period of two months.

Dematiaceous fungal keratitis following penetrating keratoplasty.

A keratitis with an unusual, sessile, filamentary mass extending into the anterior chamber developed in a patient three weeks after penetrating keratoplasty. The causative organism was identified as Exophilia (Wangiella) dermatitidis, a dematiaceous fungus. The infection was cured with a combination of medical and surgical therapy. Inoculation of the isolate into rabbit corneas produced a similar keratitis from which the same organism was cultured. Miconazole levels measured in corneal tissue removed at surgery were approximately 25 times greater than the minimum inhibitory concentration for the fungal isolate.

Analysis of the Hessburg-Barron vacuum trephine.

We tested the Hessburg-Barron vacuum trephine on 23 human cadaver eyes for accuracy and quality of cut. The trephine was found to make accurate, spherical cuts in the anterior corneal stroma. With penetration, the cut became beveled, leaving the posterior corneal button diameter larger than the anterior diameter especially if the trephine was lifted. The results are discussed relative to conventional techniques.

2.5% v 10% phenylephrine in maintaining mydriasis during cataract surgery.

A 10% viscous solution of phenylephrine hydrochloride was more effective than a 2.5% aqueous solution of phenylephrine hydrochloride in maintaining mydriasis during extracapsular cataract surgery. The pupil area after nucleus expression was 57% larger with the stronger phenylephrine concentration. The difference in pupil area was greater in darkly pigmented irides (114%) than in moderately pigmented (70%) or lightly pigmented irides (12%). Mean BP elevations following phenylephrine administration were not higher in the group receiving the 10% solution than in the group receiving the 2.5% solution. In darkly pigmented irides, a 10% viscous solution of phenylephrine hydrochloride is more effective than a 2.5% concentration in maintaining mydriasis during cataract surgery.

Vaulting characteristics of flexible loop anterior chamber intraocular lenses.

Fourteen flexible loop anterior chamber intraocular lenses were tested under controlled laboratory conditions. Lens vault was precisely measured as a function of loop compression and of force applied to the loops. A wide range of vaulting characteristics were observed. Some lenses did not vault at all while others vaulted more than the amount of compression. Advantages, disadvantages, and possible clinical implications of lens vault are discussed.

Oxygen permeability of rabbit and human corneal stroma.

Oxygen permeability (Dk) of 15 rabbit and 19 human cornea stromal samples was measured by conventional polarographic means at 36 C. Hydration and thickness were also measured. Rabbit stromal permeability was found to be about 26 X 10(-11) ml O2 cm2/sec ml mmHg at normal in vivo hydration; in vivo human cornea stromal permeability is probably less than 29 X 10(-11) ml O2 cm2/sec ml mmHg.

Laboratory analysis of the Lieberman Corneal Punch.

The Lieberman Corneal Punch, an instrument for the trephination of corneal donor tissue, was tested in the laboratory on human corneas preserved in McCarey-Kaufman (M-K) medium. Excellent corneal buttons were produced using 7.5-and 8.0-mm trephine blades, but trephination quality was variable using 8.5 and 9.0 mm blades. Modification of the curvature of the punching well may improve the trephination quality with the larger trephine blades.

Maintenance of mydriasis with epinephrine during cataract surgery.

The pupillary response to various doses of intraocular epinephrine (0.1 ml of 1:16,000, 1:32,000, 1:64,000, 1:80,000, or 1:96,000) was studied in 55 consecutive patients during extracapsular cataract surgery. The 1:16,000 epinephrine concentration provided a mean 0.74 mm increase in pupil diameter (range 0.0 to 1.7 mm) when administered to re-dilate the pupil after nucleus expression. The mean increase in pupil area with 1:16,000 epinephrine was 27% which greatly facilitated removal of lens cortex in most cases. However, 25% of all pupils failed to dilate with epinephrine 1:16,000. The other concentrations provided essentially the same mydriasis as the 1:16,000 concentration. Pupils smaller than 6 mm dilated more easily than pupils larger than 6 mm. Iris color, age, or sex had no significant effect on the mydriatic response. It is concluded that an extremely dilute concentration of epinephrine (i.e., 1:96,000 or less) may be effective in maintaining mydriasis during cataract surgery.

Familial, congenital paralysis of horizontal gaze.

Eye movements were studied in a sister and brother with familial, congenital paralysis of horizontal gaze. Horizontal and vertical eye movements were recorded with DC electro-oculography and analyzed with a laboratory computer. All horizontal, conjugate eye movements were absent (saccades, pursuit, optokinetic nystagmus, vestibulo-ocular response, and visual-vestibular responses). Voluntary vergence eye movements were preserved and were used to track visual targets. An involuntary, horizontal, pendular nystagmus was found to represent disconjugate, smooth, vergence eye movements. Vertical saccades and vestibulo-ocular responses were normal. However, vertical pursuit, optokinetic nystagmus, and suppression of the vestibulo-ocular response by fixation were impaired. A developmental anomaly affecting motor neurons and interneurons in the abducens nuclei is suggested to be the cause of the absence of conjugate, horizontal eye movements.

Complications of contact lens wear after radial keratotomy in an animal model.

In 12 rabbits radial keratotomy was performed on one eye with no treatment to the contralateral eye. Cellulose acetate butyrate contact lenses were fitted bilaterally for extended wear. The eyes were monitored weakly for three weeks with a standardized slit-lamp grading method. Corneal neovascularization occurred earlier and progressed further in eyes that had radial keratotomy than in the control eyes (P less than .0025). These results suggested that patients who require contact lenses after radial keratotomy may be at higher risk for complications such as corneal neovascularization.

Inhibitors of surgically induced miosis.

Miosis induced by surgical trauma is a frequent problem during extracapsular cataract surgery. In experimental surgery on rabbits, the inhibitory effect on pupillary constriction of cyclo-oxygenase inhibitors, local anesthetics, capsaicin (presumed substance P depletor), sympathomimetic agents, and anticholinergic agents were studied. In eyes predilated with tropicamide, iris massage caused marked pupillary constriction. Randomized pretreatment with the following agents significantly inhibited miosis: flurbiprofen, P less than 0.005; topical anesthetics (benoxinate, P less than 0.001, cocaine, P less than 0.05, proparacaine, P less than 0.005); and retrobulbar capsaicin, P less than 0.005. No significant inhibition was shown with topical indomethacin aqueous solution (P less than 0.15), topical tetracaine (P less than 0.15), or retrobulbar lidocaine (P less than 0.15). No single agent or combination of agents blocked the total miotic response; however, a combination of flurbiprofen, benoxinate, and capsaicin blocked more than two third of the miosis. Phenylephrine, a sympathomimetic (active) mydriatic agent, was more effective than anticholinergic (passive) mydriatic agents in obtaining maximal pupillary size after surgical iris massage.

Flurbiprofen in the treatment of corneal neovascularization induced by contact lenses.

Cellulose acetate butyrate extended-wear contact lenses were fitted bilaterally on ten New Zealand albino rabbits. We administered flurbiprofen 0.03% solution topically to the experimental eyes and vehicle solution to the contralateral control eyes four times a day in a random, masked fashion beginning 24 hours before the contact lens was fitted. Corneal neovascularization, which developed in all eyes by the 25th day of contact lens wear, was significantly suppressed by flurbiprofen treatment (mean vessel length was 1.5 +/- 0.4 mm for the treated eyes and 3.0 +/- 0.3 mm for the control eyes; P less than .005). Topical administration of a noncorticosteroidal anti-inflammatory agent may be an effective treatment for corneal neovascularization induced by contact lenses.

Suppression of adrenergic adaptation in the eye with a prostaglandin synthesis inhibitor.

The treatment of glaucoma patients with a topical medication is sometimes associated with adaptation (the development of subsensitivity) to the effect of the medication. In the rabbit eye, adaptation develops when norepinephrine is administered topically on a daily basis. A marked decrease in the intraocular pressure is observed the first day, but diminishing responses are observed on subsequent days. Since prostaglandins may be released in response to catecholamines and have been found to inhibit adrenergic neurotransmission, we treated rabbits with topical flurbiprofen, a potent cyclooxygenase (prostaglandin synthesis) inhibitor, to suppress adaptation to norepinephrine. The results demonstrate a significant suppression of adaptation in the concentration range of 0.001% flurbiprofen (p less then 0.0005). This finding supports the theory that cyclooxygenase products mediate the development of adaptation to exogenous norepinephrine in the rabbit eye.

Small malignant melanoma of the choroid with extraocular extension.

A disciform macular lesion in the hyperpigmented eye of a patient with melanosis oculi demonstrated slowly progressive increase in size during eight years. Clinical observation and serial fundus photography indicated increase in anteroposterior thickness of the lesion to 2.0 mm and in greatest diameter from 3.5 to 6.0 mm. Subsequent echography revealed an overall anteroposterior dimension of 3.4 mm and an increase to 5.5 mm in 20 months. Enucleation of the affected eye with the intact extraocular tumor mass and a local tenonectomy demonstrated a choroidal malignant melanoma of the epithelioid cell type with extraocular extension, peripapillary scleral infiltration, focal invasion of the juxtalaminar optic nerve, and tumor cells in the subarachnoid space. This experience emphasizes the importance of echography in the periodic evaluation of small choroidal malignant melanomas to detect growth not apparent by ophthalmoscopy.

Melanosis oculi, small choroidal melanoma, and extraocular extension.

In a white patient with melanosis oculi, a small choroidal melanoma in the hyperpigmented eye was observed for 8 years before enucleation. An important factor in the decision to enucleate was echographic evidence of extraocular tumor extension. Histopathologic examination confirmed the presence of a small choroidal melanoma (with an intraocular tumor volume of about 60 mm3), scleral tumor infiltration, and extrascleral tumor extension. Discussion considered the reported association of melanosis oculi with uveal melanoma in white patients, the extremely important role of echography in the management of even small choroidal melanomas, and the significance of extraocular tumor extension.