Jonathan H. Talamo

Femtosecond laser capsulotomy.

PURPOSE: To evaluate a femtosecond laser system to create the capsulotomy. SETTING: Porcine and cadaver eye studies were performed at OptiMedica Corp., Santa Clara, California, USA; the human trial was performed at the Centro Laser, Santo Domingo, Dominican Republic. DESIGN: Experimental and clinical study. METHODS: Capsulotomies performed by an optical coherence tomography–guided femtosecond laser were evaluated in porcine and human cadaver eyes. Subsequently, the procedure was performed in 39 patients as part of a prospective randomized study of femtosecond laser‐assisted cataract surgery. The accuracy of the capsulotomy size, shape, and centration were quantified and capsulotomy strength was assessed in the porcine eyes. RESULTS: Laser‐created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 μm ± 26 (SD) for the laser technique and 337 ± 258 μm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 ± 47 μm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 ± 21 mN for 3 μJ, 121 ± 16 mN for 6 μJ, and 113 ± 23 mN for 10 μJ. The strength of the manual capsulorhexes was 65 ± 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique. Financial Disclosure: The authors have equity interest in OptiMedica Corp., which manufactures the femtosecond laser cataract system.

Femtosecond Laser–Assisted Cataract Surgery with Integrated Optical Coherence Tomography

An image-guided, femtosecond laser can create precisely placed, accurate cuts in the eye to improve cataract surgery. The Power of Light As Star Wars fans know, a lightsaber fares better against the Dark Force than does a metal sword. Ophthalmologists, who battle the darkening forces of eye disease, have also learned this lesson, replacing steel scalpels with lasers for creating precise, controlled incisions in the eye. Laser-assisted in situ keratomileusis—commonly known as LASIK surgery—corrects myopia (nearsightedness) and other refractive errors in millions of people each year. Now, Palanker et al. used this approach to devise a more precise, reproducible and automated way to remove cataracts. The authors combine the precise cuts of a laser with the imaging sophistication of optical coherence tomography, a method that uses interference of coherent light scattered by biological tissues to create three-dimensional images of their internal structure. On the basis of the individual patient’s eye anatomy, the laser system calculates the optimal set of cutting patterns for cataract removal and directs the laser to execute these slices, resulting in fast, clean surgery. Two light-based methods made this surgical advance possible. The first, the femtosecond laser, is ideal for use deep inside a fragile eye. Unlike longer pulse lasers, which melt and boil their targets away, producing significant collateral damage to adjacent structures, femtosecond light pulses can turn the material in the focal spot into ionized plasma, allowing dissection of transparent tissues without heat accumulation and minimal disturbance to the surroundings. The resulting cut is smooth and precise. The second method—optical coherence tomography (OCT)—takes advantage of slight variations in the refractive properties of living tissues. Coherent light scattered by structures within the eye allows reconstruction of a 3D image of the live tissue. Palanker et al.’s instrument uses this imaging technique to map the cornea, iris and crystalline lens within the patient’s eye and precisely position the various laser cuts. The laser makes a circular opening in the lens capsule (the membrane that surrounds the lens itself), sections the opaque lens into small pieces that are easily removed, and carves a partial incision in the cornea for later completion of surgery and insertion of the artificial lens under sterile conditions. The laser-created edges in the lens capsule are stronger than those made manually, so they better resist damage when the opaque lens is removed or the new lens is implanted. All the laser cuts are produced without perforating the cornea, so that the procedure can be performed outside the operating room. The laser can also be used to cut the corneal surface for correction of astigmatism and for creating a port for surgical instruments in the operating room. Although the new instrument plans and performs incisions much more accurately than do currently available tools, a surgeon still must remove the lens manually. The benefits of the more precise surgical incisions on visual acuity in patients with various types of intraocular lenses will need to be ascertained in a larger prospective trial, although the preliminary data in the paper are promising and indicate that the laser procedure is safe for ocular tissues. This new instrument will arm surgeons with a precise and automated lightsaber with which to battle the darkening forces of cataracts. About one-third of people in the developed world will undergo cataract surgery in their lifetime. Although marked improvements in surgical technique have occurred since the development of the current approach to lens replacement in the late 1960s and early 1970s, some critical steps of the procedure can still only be executed with limited precision. Current practice requires manual formation of an opening in the anterior lens capsule, fragmentation and evacuation of the lens tissue with an ultrasound probe, and implantation of a plastic intraocular lens into the remaining capsular bag. The size, shape, and position of the anterior capsular opening (one of the most critical steps in the procedure) are controlled by freehand pulling and tearing of the capsular tissue. Here, we report a technique that improves the precision and reproducibility of cataract surgery by performing anterior capsulotomy, lens segmentation, and corneal incisions with a femtosecond laser. The placement of the cuts was determined by imaging the anterior segment of the eye with integrated optical coherence tomography. Femtosecond laser produced continuous anterior capsular incisions, which were twice as strong and more than five times as precise in size and shape than manual capsulorhexis. Lens segmentation and softening simplified its emulsification and removal, decreasing the perceived cataract hardness by two grades. Three-dimensional cutting of the cornea guided by diagnostic imaging creates multiplanar self-sealing incisions and allows exact placement of the limbal relaxing incisions, potentially increasing the safety and performance of cataract surgery.

Reproducibility of Flap Thickness With IntraLase FS and Moria LSK-1 and M2 Microkeratomes

PURPOSE To compare flap thickness reproducibility of the femtosecond laser and two mechanical microkeratomes. METHODS Flap thickness for all eyes was measured as the difference between the preoperative (day of surgery) full corneal thickness and post-flap creation central stromal bed thickness using ultrasonic pachymetry. Flap thickness values produced by three different microkeratome systems were compared for accuracy and reproducibility. RESULTS For 99 flaps created using the IntraLase FS laser with an intended thickness of 110 microm, the mean achieved thickness was 119 +/- 12 microm (range: 82 to 149 microm). In 100 eyes treated with the Moria LSK-1 microkeratome with an intended flap thickness of 160 microm, the mean achieved thickness was 130 +/- 19 microm (range: 71 to 186 microm). In 135 eyes treated with the Moria M2 microkeratome with an intended flap thickness of 130 microm, mean thickness was 142 +/- 24 microm (range: 84 to 203 microm). The standard deviation and range of corneal flap thickness created with the IntraLase FS laser was significantly smaller than either mechanical microkeratome (P < .0001). CONCLUSIONS When compared to two commonly used mechanical microkeratomes, mean achieved flap thickness was more reproducible with the IntraLase FS laser, reducing the comparative risk of overly thick flaps.

Late traumatic dislocation of laser in situ keratomileusis corneal flaps

PURPOSE To report the management and outcome of late-onset traumatic dislocation of laser in situ keratomileusis (LASIK) flaps. DESIGN Retrospective, observational case series. PARTICIPANTS Four patients with late-onset LASIK flap dislocation occurring after mechanical trauma at various intervals (10 days-2 months) after the procedure. INTERVENTION In all cases of postoperative traumatic LASIK flap dislocation, the flap was refloated with scraping and irrigation of the underlying stromal bed within 12 hours of the injury. A bandage contact lens was placed, and a regimen including topical antibiotics and corticosteroids was instituted in all cases. MAIN OUTCOME MEASURES Best spectacle-corrected visual acuity and complications associated with the surgery were monitored. RESULTS Postoperative follow-up ranged from 4 to 21 months. Nonprogressive epithelial ingrowth was noted in one patient and diffuse lamellar keratitis developed in another patient. All patients recovered pretrauma spectacle-corrected visual acuity. CONCLUSIONS Corneal LASIK flaps are prone to mechanical dislocation as late as 2 months after the procedure. Appropriate management results in recovery of optimal visual outcomes.

Intacs for keratoconus and post-LASIK ectasia: mechanical versus femtosecond laser-assisted channel creation.

Purpose: To evaluate the efficacy of intracorneal ring segments to treat keratoconus and post-laser in situ keratomileusis (LASIK) keratectasia implanted by using either mechanical dissection or a femtosecond laser. Methods: Thirty-three eyes of 29 patients had intracorneal ring segments implanted by using mechanical dissection (17 eyes) or a femtosecond laser (16 eyes). Mean follow-up was 10.3 months. Parameters assessed before and after surgery included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), refractive cylinder (RC), best contact lens-corrected visual acuity (BCLVA), and contact lens tolerance. Results: Statistically significant changes occurred for all parameters when we analyzed all 33 eyes as 1 group. Mean UCVA LogMar values improved from 1.0 ± 0.3 (20/200) to 0.6 ± 0.4 (20/80) (P < 0.0005). Mean BSCVA changed from 0.3 ± 0.2 (20/40) to 0.2 ± 0.2 (20/30) (10%; P < 0.05), and MRSE from −9 ± 4 to −7 ± 4 D (P < 0.05; 20%). There was a decrease of 0.5 D or more of RC in 62% of eyes. BCLVA improved from 0.2 ± 0.2 (20/30) to 0.1 ± 0.1 (20/25) after surgery (P < 0.02). Contact lens tolerance improved in 81% of eyes. There was no statistically significant difference in outcomes between mechanical dissection and femtosecond laser-assisted techniques. However, although statistical power was adequate to detect changes in clinical parameters as a result of surgery, it was not sufficient to conclusively show such differences between surgical techniques. Conclusions: For mild to moderate cases of keratoconus and post-LASIK keratectasia, the use of a femtosecond laser for Intacs channel creation seems as effective as mechanical dissection. Future studies are warranted to further evaluate channel creation by a femtosecond laser.

Cyclotorsion in the seated and supine patient

Abstract We used Maddox double‐rod measurements to determine if positionally induced ocular cyclotorsion occurs when a patient moves from the seated to supine position. Maddox double‐rod measurements were determined twice while patients (N = 30) viewed a fixation light at a distance of 7 feet in both the seated and supine positions. The difference between axis measurements made in seated and supine positions was not statistically significant. There was also no significant difference between the two measurements made in the seated and in the supine positions. These data show that the eyes do not undergo positionally induced ocular cyclotorsion when a patient moves from a seated to a supine position.

Optical patient interface in femtosecond laser-assisted cataract surgery: Contact corneal applanation versus liquid immersion

Purpose To compare 2 optical patient interface designs used for femtosecond laser–assisted cataract surgery. Setting Optimedica Corp., Santa Clara, California, USA, and Centro Laser, Santo Domingo, Dominican Republic. Design Experimental and clinical studies. Methods Laser capsulotomy was performed during cataract surgery with a curved contact lens interface (CCL) or a liquid optical immersion interface (LOI). The presence of corneal folds, incomplete capsulotomy, subconjunctival hemorrhage, and eye movement during laser treatment were analyzed using video and optical coherence tomography. The induced rise of intraocular pressure (IOP) was measured in porcine and cadaver eyes. Results Corneal folds were identified in 70% of the CCL cohort; 63% of these had areas of incomplete capsulotomies beneath the corneal folds. No corneal folds or incomplete capsulotomies were identified in the LOI cohort. The mean eye movement during capsulotomy creation (1.5 sec) was 50 μm with a CCL and 20 μm with an LOI. The LOI cohort had 36% less subconjunctival hemorrhage than the CCL cohort. During suction, the mean IOP rise was 32.4 mm Hg ± 3.4 (SD) in the CCL group and 17.7 ± 2.1 mm Hg in the LOI group. Conclusions Curved contact interfaces create corneal folds that can lead to incomplete capsulotomy during laser cataract surgery. A liquid interface eliminated corneal folds, improved globe stability, reduced subconjunctival hemorrhage, and lowered IOP rise. Financial Disclosure Drs. Talamo, Culbertson, Batlle, Feliz, and Palanker are consultants to and Messrs. Gooding, Angeley, Schuele, Marcellino, and Andersen, and Ms. Essock‐Burns are employees of Optimedica Corp., Sunnyvale, California, USA.

A Prospective Evaluation of Alcohol-assisted versus Mechanical Epithelial Removal Before Photorefractive Keratectomy

OBJECTIVE The purpose of the study is to compare alcohol-assisted versus mechanical debridement of the corneal epithelium before photorefractive keratectomy (PRK) for low-to-moderate myopia. DESIGN A prospective study was performed on a group of consecutive patients operated on at the Massachusetts Eye and Ear Infirmary from February to April 1996 and followed for 6 months. PARTICIPANTS Eighty patients (eyes) were divided in 2 groups: 40 alcohol and 40 mechanical. INTERVENTION The patients underwent PRK for myopia (-1.5 to -7.5 diopters) with a Summit Apex excimer laser. The corneal epithelium was removed either with 20% ethanol or with a scalpel blade. MAIN OUTCOME MEASURES The two groups were compared for epithelial removal time, epithelial defect size at the end of surgery, and rate of re-epithelialization. Uncorrected visual acuity (UCVA), refractive outcome, best-corrected visual acuity (BCVA), and subjective haze were measured at 4 days and at 1, 3, and 6 months. In an additional short-term study, 40 patients (20 alcohol, 20 mechanical) had intraoperative pachymetry performed. RESULTS Alcohol-assisted de-epithelialization was faster than mechanical debridement (107 [+/-20.6 standard deviation] versus 141 [+/-30.5] seconds [P < 0.0001]) and led to a more circumscribed and reproducible epithelial defect at the end of surgery (87,739 [+/-11,852] versus 103,518 [+/-33,942] square pixels [t test, P = 0.04; f test, P = 0.001]). At 4 days, 95% of the alcohol-treated patients had healed compared with 78% of the mechanically scraped patients (Fishers exact test, P = 0.04). The alcohol group had a better UCVA at 4 days (logarithm of the minimum angle of resolution UCVA 0.36 [+/-0.22] versus 0.51 [+/-0.26]) and at 1 month (0.14 [+/-0.17] versus 0.22 [+/-0.16] [Mann-Whitney U test, P = 0.02 and P = 0.03]) but equalized at 3 months (0.10 [+/-0.14] versus 0.13 [+/-0.16]) and at 6 months (0.11 [+/-0.15] versus 0.14 [+/-0.13] [Mann-Whitney U test, P = 0.23 and P = 0.34]). There was a trend toward less subjective haze in the alcohol-treated patients over the course of the study (area under the curve, 71.9 [+/-35.3] versus 87.9 [+/-33.8] [Mann-Whitney U test, P = 0.07]). The difference from target was equivalent in both groups at 6 months (-0.22 [+/-0.58] diopter in the alcohol group and -0.43 [+/-0.52] diopter in the mechanical group [t test, P = 0.14; f test, P = 0.57]). There were no differences in intraoperative pachymetry, corneal uniformity index as calculated from the corneal topography, and loss of BCVA between the two groups. CONCLUSIONS Twenty percent ethanol is a simple, safe, and effective alternative to mechanical scraping before PRK and appears to be associated with a quicker visual rehabilitation.

Natural history of corneal astigmatism after cataract surgery

ABSTRACT Little information on the natural course of corneal astigmatism following cataract surgery exists. We report a prospective, computerized analysis of postoperative astigmatism, based on keratometry measurements, of 137 cases of extracapsular cataract extraction with intraocular lens implantation performed by one surgeon. No sutures were cut postoperatively. Surgery induced 1.44 diopters (D) of with‐the‐rule astigmatism at one month, which declined at a rate of 0.77 D and 0.35 D per month for the next two months, respectively, with a more gradual decline thereafter. The mean surgically induced astigmatism at the last postoperative visit ranged from 0.29 D at six months (minimum follow‐up) to 1.23 D at 48 months; both were against‐the‐rule. Mean follow‐up was 28.92 months. These findings may be technique specific and suggest that (1) corneal curvature continues to change slowly even two to four years postoperatively; (2) most patients develop against‐the‐rule astigmatism, thus more with‐the‐rule astigmatism is desirable in the early postoperative period; (3) selective suture removal is necessary only when significantly more than 3.00 D of surgically induced with‐the‐rule astigmatism is present.

Comparison of Suture-in and Suture-out Postkeratoplasty Astigmatism With Single Running Suture or Combined Running and Interrupted Sutures

PURPOSE To evaluate postkeratoplasty astigmatism between two suture techniques 2 to 4 years postoperatively in a group of patients previously studied 9 months postoperatively. METHODS Thirty-two patients who underwent penetrating keratoplasty were randomly assigned to one of two groups. Group 1 (16 patients) had a 24-bite single running 10-0 nylon suture with postoperative suture tension adjustment; group 2 (16 patients) had combined 16-bite running and eight interrupted 10-0 nylon sutures with selective postoperative removal of interrupted sutures. During long-term follow-up, the running suture was removed in 19 patients (59%). RESULTS Postoperative astigmatism was slightly lower in patients with the single running suture technique when sutures were in place and was slightly greater after the sutures were removed compared with the combined running and interrupted suture technique (sutures in: single running suture +/- SD, 2.6 +/- 1.2 diopters [five patients, 31%]; combined running and interrupted sutures, 3.8 +/- 1.1 diopters [eight patients, 50%]; sutures out: single running suture, 3.3 +/- 1.3 diopters [11 patients, 69%]; combined running and interrupted sutures, 2.8 +/- 1.5 diopters [eight patients, 50%]). These differences were not statistically significant (sutures in, P < .13; sutures out, P < .46). Averages of follow-up were group 1,48.3 +/- 10.6 months and group 2, 46.3 +/- 13.0 months. Follow-up ranged from 23 to 60 months. CONCLUSIONS Postoperative astigmatism 4 years after penetrating keratoplasty is similar for these two suturing techniques, with or without residual sutures. A single running suture results in more rapid visual rehabilitation and less early astigmatism compared with the combined interrupted and running suture technique.