Irrigating irises, aperture inlays and driving safely

September 11, 2012

The lectures covered by OTEurope included a study on irrigating iris retractors, a small aperture inlay for presbyopia, an IOL that enables safe car driving, an explanation on corneal incisions via femtosecond laser surgery and how pupil dilation affects IOL position.

Small aperture inlay successful in presbyopia


Small aperture inlay implantation improves near and intermediate visual acuity (VA) in presbyopic patients, explained Dr Durrie at the Corneal Inlays lecture yesterday.
The prospective, non-randomized clinical trial, entitled "Small aperture corneal inlay for presbyopia: 24 month results-to-date" involved 507 presbyopic emmetropes based at 24 sites throughout the world.
The spherical equivalent of the patients varied between + 0.50 D and -0.75 D. Uncorrected near visual acuity (UNVA) had to be poorer than 20/40 and better than 20/100 and best-corrected distance acuity (BCDVA) had to be 20/20 bilaterally. There was a mean gain of 3.5 lines of near acuity between the preoperative visit and the 24-month follow-up.
Dr Durrie explained, "Mean uncorrected intermediate visual acuity improved one line from the preoperative visit to 20/25, mean UDVA was 20/20 and binocular uncorrected distance visual acuity stayed at 20/16 throughout the investigation."

Pupil dilation effects IOL positioning


Degree of pupil dilation influences IOL position, reveals Prof Wolffsohn's study featured in the free abstract session Pupil Management and Phaco Tips.
Professor Wolffsohn presented the findings of his study "Stability of pupil dilation following cataract surgery" during yesterday's lecture. The investigation covered 204 patients across six European sites.
All eyes were dilated using phenylephrine 2.5% and tropicamide 1.0%, with pupils imaging after 30 minutes using a digital slit-lamp biomicroscope at the operative visit and 1-2 days, 7-14 days, 30-60 days and 120-180 days at follow-up.
After cataract surgery a significant inferior shift in pupil centration was observed over time, but there was no change in horizontal centration. IOL centration was stable with respect to the limbus, but was vertically decentrated compared to the pupil.
Pupil width and height were both significantly larger after surgery and the ratio between them was significantly altered.
“This research confirms that when the pupil is pharmacologically dilated for cataract surgery it cannot be used as a satisfactory guide for centration,” concluded Professor Wolffsohn.
“The limbus is a better guide, although the pre-dilation pupil decentration relative to the limbus also needs to be taken into account when positioning an IOL. Such knowledge becomes even more critical when premium IOLs are to be implanted because of their more complex optical designs which can cause a significant reduction in visual quality if they are not perfectly centred. In addition, research is warranted into the development of new surgical IOL implantation techniques and IOL materials and designs that to not impair the dilation response.”

Properties of corneal incisions with femto explained


Dr Julia Stevens explained the mechanical and physiological properties of performing corneal incisions with a femtosecond laser in the Femto Cataract Surgery lecture on Monday.
Dr Stevens presented her paper "Femtosecond laser corneal incisions for cataract surgery" with the aim to verify the mechanical properties of the procedure. The study included 8 cadaver eyes and 24 porcine eyes that underwent corneal incisions including arcuate, primary cataract and side-port incisions.
Laser incision placement and incision geometry were both manually validated. In 8 of the 24 porcine eyes arcuate, primary cataract, side-port incisions, and manual incisions were completed to evaluate endothelial cell damage. Damage was assessed based on stained cell images.
Water tightness and blunt dissection capability was seen in all 32 eyes with the femtosecond laser procedure. All necessary incisions were performed in all locations, along with the appropriate geometry based on visual and manual inspection. The laser incisions caused less endothelial cell damage than manual incisions.

Irrigating iris retractor manages small pupil


The irrigating iris retractor manages small pupils that appear during cataract surgery, claimed Dr Bohm yesterday.
Dr Bohm, speaking at the Pupil Management and Phaco Tips lecture, compiled a paper entitled "Managing of constricted pupil with irrigating iris retractor". The retractor was inserted in the pupil margin and slides around to enable the visualisation of the cortical remnants in the equatorial area of the capsule. The retractor was then switched from hand to hand, meaning the surgeon could visualize the entire equatorial area.
A video was shown to the audience depicting the procedure. The retractor is able to create the capsulorhexis in eyes with complicated cataract caused by central posterior synechias. The surgeon is able to check the position of the IOL and implant a toric IOL to visualize toric alignment.
Using the irrigating iris retractor is a possible management option for small pupils in cataract surgery and can be completed without additional incisions.

Safe car driving enabled with IOL


Synchrony dual-optic accommodating IOL implantation for macular degeneration has produced excellent clinical outcomes.
Dr Piovella revealed the results of the study "Quality of vision with dual-optic accommodating IOL: 1 year clinical results" during the lecture Cataract Surgery Outcomes.
The IOLs were implanted in 30 eyes and follow-ups were completed on the same day, day one, one week, one month, three months, six months and one year, postoperatively. The outcome measures included contrast sensitivity, halos and glare rate.
Far uncorrected visual acuity was 0.46 ± 0.21, 0.80 ± 0.19, 0.85 ± 0.21, 0.91 ± 0.21 and 0.99 ± 0.03 at one month, three months, six months and one year, respectively. All patients were able to read in 16/20 vision without correction and there were no complications.
Dr Piovella commented, "Moderate halos were only present in 10.2% of patients and there was no contrast sensitivity penalization. The IOL allows 100% light distribution for far and near vision. YAG laser surgery was performed in two of the 30 eyes due to posterior capsule opacification (PCO)."
Uncorrected far vision that enabled the safe driving of a car was achieved in all patients within two months and intermediate and near vision were achieved within one week.