An assessment of intraocular pressure rise in patients with gas-filled eyes during simulated air flight.

PURPOSE: To investigate the safety of aircraft flight for patients with small volumes of residual postoperative intraocular gas. DESIGN: Nonrandomized comparative trial. PARTICIPANTS: Seventeen eyes (nine gas filled and eight control eyes) of nine patients and one eye of one control subject were tested. METHODS: Patients with postoperative intraocular gas and the control subject were tested in the controlled environment of a hypobaric chamber to simulate the cabin depressurization associated with a typical commercial aircraft flight. Before, during, and after a simulated flight, the intraocular pressure (IOP) in the gas-containing and contralateral eyes was tested using the Perkins (Edinburgh, UK) and Tono-Pen XL (Jacksonville, FL) tonometers. MAIN OUTCOME MEASURES: The absolute and percentage change in IOP with varied cabin pressurization. RESULTS: Of the nine patients with intraocular gas, seven had 10% to 15% gas volume and two had 20% gas volume. In the 10% to 15% gas volume group, the IOP rose by an average of 109% from baseline during ascent to an average cabin altitude of 7429 feet above sea level. The IOP dropped to an average of 30% above baseline IOP during the cruise phase and further decreased to an average of 38% below baseline IOP on return to baseline altitude. In the 20% gas volume group, the IOP rose by an average of 84% from baseline during ascent to an average cabin altitude of 3400 feet above sea level. The IOP dropped to an average of 42% below baseline IOP on return to baseline altitude. The IOP in the contralateral control eyes did not vary with altitude changes. No patient experienced pain or visual loss during the experiments. CONCLUSIONS: Our results demonstrate that IOP may rise significantly in gas-filled eyes during simulated air flight, supporting the current conservative recommendation against air travel for most patients with intraocular gas bubbles. Further testing is warranted to develop a more objective measure of intraocular gas volume estimation and to define better the tolerability of aircraft flight for patients with intraocular gas.

Visual outcome following penetrating globe injuries with retained intraocular foreign bodies.

BACKGROUND: In our institution the occurrence of endophthalmitis related to intraocular foreign bodies has been rare. In this review we analyse the outcome of eyes with retained intraocular foreign bodies presenting to two vitreoretinal surgeons over nearly 7 years. METHODS: Review of the records of 26 patients who presented to two surgeons in a tertiary care vitreoretinal service in Toronto between January 1989 and November 1995. Information documented included mechanism of injury, time from injury to definitive surgery, entry site, presence of vitreous hemorrhage, type of surgery performed, initial and final visual acuity, and development of endophthalmitis. RESULTS: All the injuries occurred in male patients, with a mean age of 36.1 (range 15 to 55) years. Most of the injuries occurred in the workplace, and in most cases (17 [65.4%]) the mechanism of injury was "metal on metal." The entry site was via a perforating wound of the cornea in 16 cases (61.5%). Almost all cases were repaired within 48 hours by means of pars plana vitrectomy. Concurrent lensectomy was required in 18 cases (69.2%) for lens damage at the time of the original injury. Vitreous hemorrhage was present in 22 cases (84.6%). One patient (3.8%) manifested clinically apparent endophthalmitis, which responded to intravitreal antibiotic therapy. Nineteen eyes (73.1%) had a final visual acuity of 6/24 or better. Eyes with coexisting or subsequent retinal detachment had significantly worse vision than those without retinal detachment (p < 0.001). INTERPRETATION: The incidence of endophthalmitis in our series is lower than that in other published series. Prompt definitive treatment was associated with a good prognosis in most cases.

Bacterial endophthalmitis following extracapsular cataract extraction: recommendations for early detection.

OBJECTIVE: To determine the time between the onset of symptoms of endophthalmitis after cataract extraction and presentation to an ophthalmologist and to determine the spectrum of organisms responsible for postoperative endophthalmitis. DESIGN: Case series. SETTING: Tertiary care vitreoretinal service in Toronto. PATIENTS: Thirty-three patients with early (presentation within 2 weeks of surgery) endophthalmitis following extracapsular cataract extraction and intraocular lens implantation performed between January 1989 and December 1992. OUTCOME MEASURES: Time to presentation to an ophthalmologist, duration of symptoms, culture results. RESULTS: Twenty-two patients (66.7%) were documented to experience identifiable symptoms of endophthalmitis before presentation to their ophthalmologist; the mean time of onset of symptoms was 3.6 (standard deviation [SD] 1.7) days after surgery. Of the 22 patients 16 (72.7%) became symptomatic by the fourth postoperative day, and 21 (95.4%) experienced symptoms by the fifth postoperative day. The mean delay between onset of symptoms and presentation was 1.9 (SD 1.6) days. Bacteria were identified in 27 cases (81.8%), confirmed by culture in 23 cases (69.7%). The organisms were gram-positive in 25 (92.6%) of the 27 cases, and coagulase-negative Staphylococcus predominated. CONCLUSIONS: In our series a considerable delay existed between the development of symptoms of endophthalmitis following extracapsular cataract extraction and clinical diagnosis. This delay could be minimized by scheduling routine postoperative visits at 1 and 4 days following cataract surgery.

The range and variability of ophthalmological parameters in normal children aged 4 1/2 to 5 1/2 years.

BACKGROUND: Some standards for childhood ophthalmological variables exist. However, for most parameters, the range of variation found in normal children remains poorly defined. METHODS: We have determined the range of normal function for a number of commonly measured ophthalmological variables in 162 children, classified normal by Gold Standard ophthalmological examination. This group is representative of almost 12,000 normal children aged 4 1/2 to 5 1/2 in Nova Scotia. RESULTS: In 56.8% of eyes the visual acuity was 6/4.5. The use of a chart with crowding bars was more discriminating between differences in higher levels of acuity and highlighted differences in acuity between the two eyes. Randot stereoacuity showed a uniform, non-Gaussian distribution of scores. Cycloplegic refractive errors were distributed about a modal value of between +0.5 and +1.0 diopter. Forty percent of eyes had no detectable astigmatism. Ninety-seven percent of subjects had no heterophoria. Fusional vergence data are presented. CONCLUSION: Our results document the complete normal range for selected ophthalmological parameters in normal preschoolers. The values obtained were in general better than expected.

Distinct electroretinographic oscillatory potential generators as revealed by field distribution.

Oscillatory potentials (OPs) of the electroretinographic signal were recorded in five healthy subjects by means of dermal electrodes located at various positions along the infraorbital ridge and referred to either a frontal or a temporal electrode. Flashes of light were generated in a Ganzfeld stimulator, and OPs were recorded with the subjects' eyes in abduction and adduction. This arrangement of eyeball and electrode positions makes it possible to record the retinal activity from various axes; from a pupillary-posterior pole (longitudinal) axis to an equatorial axis. The individual OPs were found to be selectively affected by the axis of recording, thus suggesting distinct sources of generation. All the OPs reversed in polarity as the recording axis maintained by the electrodes was moved from the longitudinal to the transverse axis. The point of inversion of OP2 and OP3 was similar, as was their amplitude ratio (OP3/OP2), which remained independent of the eye position. However, OP4 became inverted at a different location, closer to the longitudinal axis, and the amplitude ratio (OP4/OP2) varied significantly with the eye position. Altogether, these results suggest different retinal source generators for OP2 and OP3, and for OP4.