Physicians in Toronto assert that simultaneous bilateral cataract surgery does not lead to an increased incidence of intraoperative or postoperative complications.
The researchers retrospectively reviewed the results of 1,020 consecutive patients (2,040 eyes). All had SBCS by endolenticular phacoemulsification through a clear-corneal incision on the corneal steep axis with foldable posterior-chamber IOL implantation. The procedures were managed as separate consecutive surgeries under topical and intracameral anesthesia and were performed by the same surgeon. Complications are listed in Table 1. The research team believes that none of the complications would have been prevented had the surgery been performed monocularly. They note that in the hands of an experienced cataract surgeon, SBCS is cost effective for the hospital and the insurer through avoidance of duplication of patient work-up, minimization of operating-room time and reduction of hospital stay.
(J Cataract Refract Surg 2003; 29:1281-1291)
Arshinoff S, Strube Y, Yagev R
Table 1. Complications of SBCS Complication
Incidence (%) Intraoperative
Hole in PC
0.10 Postoperative RD
0.20 Ciliary Block Glaucoma
0.05 Endothelial Decompensation
0.05 Transient Mild Iritis
0.34 Severe Iritis
0.05 Transient CME Delaying Visual Recovery
0.29 Significant IOL Power Error (>0.75D)
1.32 Total Intraoperative and Postoperative
1.57 (0.54) (x) = number of eyes of total of 2,040 eyes of 1,020 patients (number of eyes requiring second procedures).
Contact Lens Wear Reduces Corneal Thickness
Canadian researchers have found a clinically significant reduction in corneal thickness measurements associated with full-time contact lens wear. They conducted a retrospective chart study and located 634 eyes that met the inclusion criterion: wearing either soft lenses or rigid gas-permeable lenses full-time (more than eight hours per day) for two years or more. Occasional or part-time lens wearers and those wearing them overnight consistently were excluded. Pachymetry measurements of control eyes (no history of CL wear) were compared to those of full-time soft and RGP lens wearers.
Soft CL wearers had a mean reduction in cor-neal thickness of 22 µm compared to the control population (P = .00001). RGP lens wearers had a reduction of 24 µm compared to controls (P = .0001). The difference in corneal thickness between the soft lens group and the RGP was not found to be clinically significant.
Breaking the soft lens group into refractive subsets (plano to -2.00 D, -2.25 to -4.00 D, etc.) did not reveal a significant difference except in the highest refractive error subset (-10.25 to -12.00 D). Here, the mean corneal thickness (553.4 µm) was greater than in all the other subsets.
In the RGP subsets, the mean corneal thickness was lowest (517.9 µm) in the highest refractive error subset (-10.25 to -12.00 D). The difference between the highest error subset and the lowest refractive error subset (plano to
-2.00 D) was significant (P = .003245). Researchers noted that a larger sample size in the highest refractive error subsets might help to clarify this trend. (J Cataract Refract Surg 2003;29:1319-1322)
Braun D, Anderson Penno E
Amadeus Accuracy and Flap Thickness
Investigators in Houston determined that, using the Amadeus (AMO, Santa Ana, Calif.) microkeratome, LASIK flap thickness correlated with central corneal thickness for the 140-µm head. They also found that reuse of the microkeratome blades produced significantly thinner LASIK flaps on the second eyes cut.
This prospective study evaluated the accuracy and predictability of the flap thicknesses obtained using the 140-, 160- and 180-µm heads for the Amadeus microkeratome. Researchers analyzed the effect on flap thickness of corneal thickness, corneal curvature, microkeratome blade oscillation and translation speeds, and blade reuse.
LASIK flaps were cut in eyes according to Table 2. The same microkeratome blade was used for bilateral cases with the right eyes always undergoing surgery first. They found that the 140-µm head tended to cut thicker flaps on corneas with greater preop corneal thicknesses, but they called this correlation "weak," with r2 values of 0.125 and 0.301 for right and left eyes, respectively.
With the 160-µm head, researchers found only a low correlation (r2 = 0.15) between flap thickness and the flat keratometric value in first (right) eyes. The 180-µm head cut thicker flaps than predicted (range 198-258 µm) and was abandoned after six eyes. The limited reuse of microkeratome blades caused, on average, a 19-µm thinner flap in the consecutive eye without associated complications.
Investigators recommend measuring corneal flap thickness intraoperatively to assure that at least 250 µm of posterior tissue is preserved for future laser retreatments.
Jackson D, Wang L, Koch D