Republished review: The world through a lens: the vision of Sir Harold Ridley

Sir Harold Ridley is recognised today as the inventor of intraocular lens implantation, one the most successful and common procedures in all of surgery. His story, however, is not largely one of triumph and public accolade. This paper reviews Ridley's invention of the intraocular lens and highlights the struggles he faced after his discovery.

The world through a lens: the vision of Sir Harold Ridley

Sir Harold Ridley is recognised today as the inventor of intraocular lens implantation, one the most successful and common procedures in all of surgery. His story, however, is not largely one of triumph and public accolade. This paper reviews Ridley's invention of the intraocular lens and highlights the struggles he faced after his discovery.

Color Doppler imaging of retrobulbar hemodynamics in Sturge-Weber syndrome-associated glaucoma

PURPOSE

Sturge-Weber syndrome (SWS) is frequently associated with early onset glaucoma in the eye on the same side as the facial angioma. The exact cause of glaucoma in SWS is poorly understood and difficult to treat. The purpose of this study is to investigate the ocular hemodynamics of children with SWS-associated glaucoma using color Doppler imaging techniques.

METHODS

This is a prospective study of 10 pediatric patients with unilateral SWS-associated glaucoma. Color Doppler imaging was used to measure the peak systolic velocity and the end diastolic velocity of both the ophthalmic and central retinal arteries in the glaucomatous eye compared to the fellow healthy eye.

RESULTS

Twenty eyes of 10 children with SWS (6 boys) with unilateral glaucoma were included in the prospective study. The mean age of the 10 participants was 5.5 years. When compared to their contralateral normal eyes, the glaucomatous eyes had greater CDR (p<0.001) and a myopic shift (p=0.04). No significant differences were found in the measurements of ocular blood flow velocities of the ophthalmic and central retinal arteries.

CONCLUSIONS

Vascular pathology has been proposed to play a role in SWS glaucoma etiology. The authors did not find arterial retrobulbar blood flow differences between the glaucomatous and the fellow normal eye. Since the primary vascular anomaly in patients with SWS is in the venous plexus, a bigger prospective trial is warranted in order to better understand and treat children with SWS glaucoma.

The Response of Retrobulbar Vasculature to Hypercapnia in Primary Open-Angle Glaucoma and Ocular Hypertension

PURPOSE

To evaluate the physiological effects of hypercapnia on the retrobulbar vasculature in ocular hypertension (OH) and open-angle glaucoma (OAG).

METHODS

Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) of the ophthalmic (OA) and central retinal arteries (CRA) were evaluated in 12 eyes with OH and 8 eyes with OAG using color Doppler imaging. Measurements were taken before and during hypercapnia.

RESULTS

Patients with OAG were found to have increased EDV (p < 0.035) of the CRA, and decreased PSV (p < 0.097) and EDV (p < 0.098) of the OA, during hypercapnia. Patients with OH had increased PSV (p < 0.062) and EDV (p < 0.072) of the CRA during hypercapnia. Patients with OH also demonstrated a greater percent change in the calculated RI (p < 0.065) of the CRA in response to hypercapnia when compared to OAG. The mean RI of the CRA decreased during hypercapnia.

DISCUSSION

Patients with OH were found to have a normal vasodilatory response within the retrobulbar vasculature during hypercapnia resulting in increased volumetric blood flow to the retina while patients with OAG did not, suggesting there is vasospasm at or downstream from the CRA resulting in decreased volumetric blood flow to the retina.

A comparison of the effects of dorzolamide/timolol fixed combination versus latanoprost on intraocular pressure and pulsatile ocular blood flow in primary open-angle glaucoma patients

PURPOSE

To evaluate the effects of dorzolamide/timolol fixed combination (D/T) compared to latanoprost on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in primary open-angle glaucoma (POAG) patients.

METHODS

Thirty patients with POAG were randomized in an open-label, cross-over study. Intraocular pressure reduction was achieved by 4 weeks medical therapy with D/T twice daily or latanoprost 0.005% dosed once in the evening. During a 4-week run-in and a 4-week wash-out period between study arms, patients ceased use of all other glaucoma medications and used timolol maleate 0.5% twice daily. Primary efficacy variables were IOP and POBF.

RESULTS

There was no difference in baseline IOP and POBF parameters between the two study arms. Both D/T and latanoprost statistically significantly reduced IOP by 4.6 mmHg (p < 0.0001) and 3.75 mmHg (p < 0.0001) and increased POBF by 2.048 microl/second (p = 0.0030) and 2.147 microl/second (p = 0.0009), respectively. Repeated measures anova detected significant changes in POBF with treatment (p = 0.0361). Dorzolamide/timolol fixed combination statistically significantly increased pulse volume by 0.767 microl (p = 0.0087), while latanoprost therapy had no significant effect (p = 0.2407).

CONCLUSIONS

Both drugs had similar effects in terms of IOP reduction. Dorzolamide/timolol significantly increased pulse volume while latanoprost had no effect. Further studies are necessary to establish whether the enhancement of choroidal blood flow can prevent glaucoma progression.

Effect of intravenous droperidol on intraocular pressure and retrobulbar hemodynamics

PURPOSE

Topically-applied dopamine antagonists reduce intraocular pressure (IOP) and inrease retinal blood flow in animal models. We examined the acute effects of intravenous infusion of a dopamine blocker (droperidol) on these parameters in healthy humans.

METHODS

Sixteen subjects free from ocular or systemic disease (mean age 33 +/- 10 yrs) received either 5 mg i.v. droperidol over 5 minutes, or i.v. saline placebo in double-masked fashion. IOP was determined 30 and 60 minutes later, while color Doppler imaging was used to determine flow velocities in the ophthalmic, central retinal, and nasal and temporal posterior ciliary arteries 60 minutes after drug infusion.

RESULTS

30 minutes after drug infusion, IOP was reduced 6.0 mmHg as compared with baseline (p<0.001); after 60 minutes, IOP remained reduced by 3.7 mmHg (p<0.001). Placebo had no effect on IOP. While droperidol slightly elevated blood pressure and increased the calculated ocular perfusion pressure, the drug reduced visual acuity and contrast sensitivity (p<0.05). Droperidol elevated peak systolic velocity in the central retinal and nasal posterior ciliary arteries, without changing end-diastolic velocity or the resistance index in either of these vessels. Droperidol had no effect on flow velocities in the ophthalmic artery or the temporal posterior ciliary artery.

CONCLUSIONS

The rapid and marked ocular hypotension resulting from intravenous droperidol suggests that this agent may prove useful in the management of acute ocular hypertension. The retrobulbar changes consequent to the ocular tension reduction likely represent autoregulatory responses to altered ocular perfusion pressure.