Femtosecond Laser-Assisted Graft Preparation for Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To describe a technique of using a femtosecond laser to assist with graft preparation for Descemet membrane endothelial keratoplasty (DMEK). METHODS: A femtosecond laser was used to assist in graft preparation for 3 DMEK procedures. The donor cornea is mounted on a proprietary artificial anterior chamber. A partial thickness deep circular cut is made with the femtosecond laser through the endothelium, Descemet membrane, and posterior stroma. Graft preparation is then completed without the use of a corneal trephine. RESULTS: In all cases, graft preparation was successfully completed. Pterygium on a donor cornea resulted in an incomplete cut in 1 case that was finished manually. Subsequent keratoplasties resulted in clear corneas with endothelial cell counts within the expected range. CONCLUSIONS: The femtosecond laser may be a useful adjunct in graft preparation for DMEK.

Learning DMEK From YouTube.

PURPOSE: To evaluate the outcomes of the first cases of Descemet membrane endothelial keratoplasty (DMEK) performed by an anterior segment surgeon, learning the procedure, including graft preparation, primarily from watching YouTube videos. DMEK surgery was not learned during fellowship training; there was no attendance at DMEK courses, no witnessing of live surgery, and no supervision by an experienced DMEK surgeon. All graft tissue was prepared by the surgeon on the day of surgery. METHODS: This is a retrospective review of the 3-month postoperative results of the first 40 consecutive cases. The success rate of graft preparation, intraoperative and postoperative complications, spectacle-corrected visual acuity, endothelial cell density, and central corneal thickness were evaluated. RESULTS: Grafts were successfully prepared in all cases with no loss of donor tissue. DMEK surgery was successful in 39 of 40 eyes with the one failure occurring in a vitrectomized eye without an intact iris-lens diaphragm. Spectacle-corrected visual acuity was ≥6/6 in 23 of the 25 eyes without comorbidity. Mean endothelial cell density was 1515 (±474) cells/mm. Mean central corneal thickness decreased from 624 (±40) µm preoperatively to 513 (±34) µm postoperatively. CONCLUSIONS: Although formal training is desirable, good results can be obtained by an anterior segment surgeon learning DMEK, including graft preparation, without it. DMEK should no longer be considered a procedure with a long learning curve in routine cases.

Theoretical Effect of Lens Position and Corneal Curvature on the Near Focal Point of Multifocal Intraocular Lenses.

PURPOSE: To determine the effect of lens position and corneal curvature on the near focal point of different multifocal intraocular lenses. METHODS: Near focal points for various multifocal intraocular lenses were calculated using a refractive vergence formula. Median, high, and low values for lens position and corneal curvature were used. RESULTS: Lens position and corneal curvature both affected the theoretical near point of multifocal intraocular lenses. The effect was more pronounced for lower power adds. There was overlap of near focal points for the different near adds of the Tecnis multifocal lenses (AMO, Abbott Park, IL) across the range of lens positions and corneal curvatures seen in a normal population. CONCLUSIONS: Clinicians need to be aware of the effect of lens position and corneal curvature on the near focal point of intraocular lenses.

Enlarging the big-bubble during deep anterior lamellar keratoplasty.

PURPOSE: During big-bubble deep anterior lamellar keratoplasty, a bubble that is not large enough can be formed. Further air injection can result in the rupture of the posterior lamella, necessitating conversion to penetrating keratoplasty. We describe some techniques to safely enlarge the big-bubble in such a circumstance. METHODS: In cases in which a white-margin bubble forms that has extended to the trephination margin, the bubble is collapsed and the margins are extended by blunt dissection. For cases of an undersized clear-margin bubble, the bubble is enlarged by gentle injection of a cohesive ophthalmic viscosurgical device into the bubble cavity. RESULTS: Using these techniques, big-bubbles were safely extended beyond the trephination margin for both white- and clear-margin bubbles. CONCLUSIONS: An undersized big-bubble can safely be extended using blunt dissection for white-margin bubbles and ophthalmic viscosurgical device injection for clear-margin bubbles.

Changing perspective of reasons for not performing laser-assisted in situ keratomileusis among candidates in a university eye clinic.

BACKGROUND: The aim was to retrospectively analyse the reasons for not performing laser-assisted in situ keratomileusis (LASIK) surgery among refractive surgery candidates at a university eye clinic. METHODS: Case records of patients who presented to a university eye clinic between June 2005 and June 2010 for consideration for LASIK surgery were examined. Cases that did not undergo LASIK were selected for analysis. Reasons for not performing surgery in these cases were analysed. RESULTS: In total, 552 patients requested LASIK between July 2005 and June 2010 and 377 (68.3 per cent) of them received refractive surgery. Among 175 (31.7 per cent) patients who did not get LASIK, 62 (35.4 per cent) were male and 113 (64.6 per cent) were female, with a mean age at presentation of 36.4 ± 9.3 years (range: 19 to 78 years). The most common reasons for not offering LASIK were low corneal thickness (28.6 per cent), high myopia (15.4 per cent), large pupil (8.0 per cent) and keratoconus (7.4 per cent). Overall, 39 patients (22.3 per cent) changed their mind after their initial consultations with surgeons. The prevalence of rejection of LASIK decreased from 44.1 per cent between July 2005 and June 2006 to 3.5 per cent between July 2009 and June 2010. CONCLUSIONS: Reasons for not performing refractive surgery are quite diverse. Inadequate corneal thickness and change of mind after initial consultation were the most common reasons in the present study. There was a marked change in magnitude and trend of reasons for not performing LASIK over the study period. Further studies from settings other than university hospitals would be beneficial to compare the trend in patient selection.

Toxic epidermal necrolysis in a 15-month-old girl successfully treated with amniotic membrane transplantation.

A 15-month-old girl presented with rash, fever, and vesicles around the mouth that worsened after erythromycin was administered. Subsequently, she was diagnosed with toxic epidermal necrolysis. Ocular involvement was treated with repeated complete corneal, conjunctival, and lid margin coverage with amniotic membrane. She recovered with minimal ocular sequelae despite persistent systemic symptoms.

Rupture pressure of the posterior lamella obtained during big-bubble deep anterior lamellar keratoplasty.

PURPOSE: To investigate the pressure required to rupture the posterior lamella obtained during the presumed Descemet membrane-baring big-bubble technique of deep anterior lamellar keratoplasty (DALK). METHODS: DALK using the big-bubble technique was carried out on donor corneoscleral discs mounted on an artificial anterior chamber. Once the anterior lamella was removed, the chamber was connected to a mercury manometer. The pressure inside the chamber was increased until rupture occurred or the manometer reached its measurement limit. RESULTS: The deep lamella ruptured at 252 mm Hg in one cornea, at 270 mm Hg in another, and had not ruptured at 300 mm Hg (upper limit of the manometer) in the remaining 18 donor corneas. CONCLUSIONS: The posterior lamella of big-bubble DALK probably confers significant structural integrity on the globe.

Donor preparation using pneumatic dissection in endothelial keratoplasty: DMEK or DSEK?

PURPOSE: To determine if residual stroma remains on the Descemet membrane when pneumatic dissection is used to prepare donor tissue for endothelial keratoplasty. METHODS: Pneumatic dissection using a posterior peripheral needle insertion was carried out on 5 eye bank corneas. Samples were then sent for histological analysis. RESULTS: A thin layer of stroma remained on the Descemet membrane in all the samples. The average central stromal thickness was 12.4 µm (range 6.5-20.0 µm). CONCLUSIONS: Endothelial keratoplasty using pneumatic dissection to prepare donor tissue should be considered a form of Descemet stripping endothelial keratoplasty and not Descemet membrane endothelial keratoplasty. If future studies show excellent visual results using pneumatic dissection for endothelial keratoplasty, then removal of all donor stroma may be unnecessary.

Use of triamcinolone to judge needle depth in big-bubble deep anterior lamellar keratoplasty.

PURPOSE: To report a technique for judging needle depth in the corneal stroma during big-bubble deep anterior lamellar keratoplasty (DALK). METHODS: With the anterior chamber full of air, a dilute suspension of washed triamcinolone crystals is injected to "wash" over the air bubble. Some crystals are trapped between air and endothelium, making the posterior limit of the cornea easier to identify. The needle is then inserted into deep stroma, and big-bubble DALK is performed in the usual manner. RESULTS: This technique was used in 10 keratoconic eyes undergoing big-bubble DALK. No adverse effects of triamcinolone use were found in any eyes. CONCLUSIONS: This technique provides another option for surgeons who wish to accurately judge needle depth during big-bubble DALK.

Residual corneal stroma in big-bubble deep anterior lamellar keratoplasty: a histological study in eye-bank corneas.

AIM: To determine if residual corneal stroma remains on the recipient posterior lamella in big-bubble deep anterior lamellar keratoplasty (DALK). METHODS: Pneumodissection using the big-bubble technique was carried out on eye-bank corneas mounted on an artificial anterior chamber. Samples that had a successful big-bubble formation were sent for histological evaluation to determine if any residual stroma remained on the Descemet membrane (DM). RESULTS: Big-bubble formation was achieved in 32 donor corneas. Two distinct types of big-bubble were seen: the bubble had either a white margin (30 corneas) or a clear margin (two corneas). The posterior lamellae of all the white margin corneas showed residual stroma on DM with a mean central thickness of 7.0 µm (range 2.6-17.4 µm). The clear margin corneas showed no residual stroma on DM. CONCLUSION: It should no longer be assumed that big-bubble DALK, where the bubble has a white margin, routinely bares DM. True baring of DM may only occur with the less commonly seen clear margin bubble.