Safety and efficacy of gas-forced infusion (air pump) in coaxial phacoemulsification

Effect of IOP based infusion system with and without balanced phaco tip on cumulative dissipated energy and estimated fluid usage in comparison to gravity fed infusion in torsional phacoemulsification

Background

To evaluate the effect of three different combinations of tip designs and infusion systems in torsional phacoemulsification (INFINITI and CENTURION) in patients with cataract. According to the manufacturer, two unique improvements in the Centurion are: active fluid dynamic management system and use of an intrepid balanced tip. The study specifically aimed to evaluate the beneficial effects, if any, of change in tip design and infusion system individually and in combination on both per-operative parameters as well as endothelial health over 6 months.

Methods

One hundred and twenty six consenting patients of grade 4.0–6.9 senile cataract were randomized into three groups for phacoemulsification: Group A (n = 42): Gravity fed infusion system and 45⁰ Kelman miniflared ABS phaco tip; Group B (n = 42): intraocular pressure (IOP) based infusion system and 45⁰ Kelman miniflared ABS phaco tip; Group C (n = 42): IOP based infusion system and 45⁰ Intrepid balanced phaco tip. The cumulative dissipated energy (CDE), estimated fluid usage (EFU) and total aspiration time (TAT) were compared peroperatively. The endothelial parameters were followed up postoperatively for six months.

Results

The three arms were matched for age (p = 0.525), gender (p = 0.96) and grade of cataract (p = 0.177). Group C was associated with significant reductions in CDE (p = 0.001), EFU (p < 0.0005) as well as TAT (p = 0.001) in comparison to the other groups. All three groups had comparable baseline endothelial cell density (p = 0.876) and central corneal thickness (p = 0.561). On post-operative evaluation, although all groups were comparable till 3 months, by 6 months, the percentage losses in endothelial cell density were significantly lower in group C as compared to the other groups.

Conclusions

Use of an IOP based phacoemulsification system in association with use of the Intrepid balanced tip reduces the CDE, EFU and TAT in comparison to a gravity fed system with a mini flared tip or IOP based system with a mini flared tip while also providing better endothelial preservation thus favouring the use of an IOP fed system with a balanced tip.

Trial registration

Trial registration No.: CTRI/2016/06/007022.

Air Pump-Assisted Graft Centration, Graft Edge Unfolding, and Graft Uncreasing in Young Donor Graft Pre-Descemet Endothelial Keratoplasty

PURPOSE

To assess an air pump-assisted technique for graft centration, graft edge unfolding, and graft uncreasing while performing pre-Descemet endothelial keratoplasty (PDEK) using young donor grafts.

METHODS

Continuous pressurized air infusion was used for graft centration, graft edge unfolding, and graft unwrinkling.

RESULTS

Ten eyes of 10 patients underwent PDEK with donors aged below 40 years. In all eyes, the donor scrolled into tight scrolls. In all cases, the air pump-assisted technique was effective in positioning and centering the graft accurately and in straightening infolded graft edges and smoothing out graft creases and wrinkles. Endothelial cell loss was 38.6%. Postoperative best-corrected visual acuity at 6 months was 0.66 ± 0.25 in decimal equivalent. Continuous pressurized air infusion acted as a third hand providing a continuous pressure head that supported the graft and prevented graft dislocation as well as anterior chamber collapse during intraocular maneuvering. Adequate maneuvering space was available in all cases, and bleeding, if any, was tamponaded successfully in all cases.

CONCLUSIONS

Although very young donor grafts may be used for PDEK, they are difficult to center and unroll completely before floating against host stroma. An air pump-assisted technique using continuous pressurized air infusion allows successful final graft positioning even with very young donor corneas. It thus makes surgery easier as several key steps are made easier to handle. It additionally helps in tamponading hemorrhage during peripheral iridectomy, increasing surgical space, preventing fluctuations in the anterior chamber depth, and promoting graft adherence.

Optic surface changes in Intraocular lens scaffold: An ex vivo study

PURPOSE

We aimed to assess the micro injuries on the intraocular lens (IOL) optic in the IOL scaffold technique by ex vivo study.

SETTING

This study was conducted at the Tahira Research Laboratory, Dr Agarwal's Eye Hospital and Eye Research Centre, Chennai.

DESIGN

This was an experimental study.

METHODS

IOL scaffold technique was simulated in 12 caprine eyes with moderate lens changes using 12 IOLs (six acrylic hydrophilic and six polymethyl methacrylate IOL) in experimental set up. IOLs (6 mm optic diameter) were explanted from the caprine eyes immediately after the surgery and examined under light microscopy and phase contrast microscopy for anterior and posterior optic changes, and again after 24 hours. Scanning electron microscopy (SEM) was performed in IOLs with abnormalities. Two IOLs placed in caprine eyes that did not undergo scaffold procedure acted as controls. A trocar anterior chamber maintainer was used in four eyes.

RESULTS

Four out of 12 IOLs showed mark defects on the surface in mid periphery. Linear mark defects measured IOL 1 (190 μm), IOL 6 (18 μm), IOL 2 (2.33 μm, 2.3 μm, 14 μm, 14 μm) and IOL 5 (12 μm). The marks do not change after 24 hours. There were no mark defects (micro abrasions or scratches) seen on any of the IOL's in the central 4 mm of the optic anterior surface. The control IOLs showed no surface changes. The pre-experiment mark defects (n = 0) in study IOLs changed to post-experiment (n = 7), with no statistical significance obtained (p = 0.059).

CONCLUSION

IOL scaffold technique can cause microscopic optic surface changes seen as linear marks defects in the mid periphery and intraoperative fluid maintenance can reduce its incidence.

Effect of intracameral carbachol given during cataract surgery on macular thickness

To evaluate the effect of intracameral carbachol on foveal thickness in patients who underwent uneventful cataract surgery. This retrospective study included two groups: the study group patients (group 1, n = 47 eyes) had uneventful cataract surgery and received only carbachol 0.01 % for miosis; the control group patients (group 2, n = 49 eyes) had uneventful cataract surgery without carbachol or any intracameral medication(s). The groups were compared for foveal thickness after cataract surgery. All phacoemulsification plus intraocular lens implantation surgeries were performed under local anesthesia via temporal clear corneal tunnel incisions. Mean values and standard deviations were calculated for preoperative and postoperative visual acuity (VA) and foveal thickness (FT) at 1 and 4 weeks. Optical coherence tomography was used for the FT measurements, with the MM6 map program. The patients in the study and control groups had a mean age of 57.78 ± 9.07 and 59.72 ± 8.96, respectively (p = 0.355). All eyes had a significant improvement in VA. In the study group, the mean FT at the visits before and 1 and 4 weeks after surgery was 216.87 ± 21.06, 228.81 ± 30.52, and 222.94 ± 29.91 μm, respectively. For the control group, the mean FT, before and 1 and 4 weeks after surgery, was 222.53 ± 17.66, 231.67 ± 23.08, and 225.41 ± 22.59 μm, respectively. Intracameral carbachol 0.01 % had no effect on foveal thickness in patients who underwent uneventful cataract surgery.