Slitlamp, Specular, and Light Microscopic Findings of Human Donor Corneas After Laser-Assisted in Situ Keratomileusis

CLINICAL SCIENCES Slitlamp, Specular, and Light Microscopic Findings of Human Donor Corneas After Laser-assisted In Situ Keratomileusis

V. Vinod Mootha, MD; Dan Dawson, MD; Amit Kumar, MD; Joel Gleiser, MD; Clifford Qualls, PhD; Daniel M. Albert, MD

Objective: To examine slitlamp, specular, and light mi- slitlamp examination, of which 3 were confirmed by his- croscopic features of human donor corneas known to have topathologic examination. Highly reflective particles were undergone laser-assisted in situ keratomileusis (LASIK). seen by specular microscopy in the stroma of 23 (88%) of 26 LASIK donor corneas, but only 1 (4%) of 26 con- Methods: Twenty-six donor corneas known to have un- trol donor corneas had a single highly reflective particle dergone LASIK prospectively underwent slitlamp exami- in the stroma (PϽ.001). The mean central endothelial nation with particular attention to the presence of a flap cell counts were similar: 2138 cells/mm2 in the LASIK edge, as well as specular microscopy with particular at- group compared with 2250 cells/mm2 in the controls tention to the presence of highly reflective particles in (P=.39). Vacuolization and pyknosis of keratocytes the stroma corresponding to the LASIK interface. Cen- was a consistent histopathologic finding after LASIK. tral endothelial cell density and pachymetery were ob- Metallic particles at the interface were not detected by tained. They were compared with 26 control donor cor- histology. neas without LASIK. Eleven LASIK donor corneas were processed for histology. Twenty-six donor corneas with Conclusions: Detection of a flap edge by slitlamp ex- no known prior keratorefractive surgery also under- amination may detect at least half of the donor corneas went similar slitlamp examination and specular micros- that may have undergone LASIK. The detection of highly copy to serve as controls. reflective stromal particles may form an effective basis for screening for LASIK donor corneas using specular mi- Results: Twelve (46%) of 26 LASIK donor corneas had croscopy and requires further study. an obvious flap edge, and 10 (39%) had a subtle flap edge by slitlamp examination. Four (15%) had infiltrates by Arch Ophthalmol. 2004;122:686-692

N 2001, THE 80 EYE BANKS OF THE quired to protect the donor cornea pool. Eye Bank Association of America Corneal topography and pachymetry,3,4 provided tissue for 46532 cor- videokeratography,5,6 dark-field biomi- neal transplantation proce- croscopy,7 wavefront analysis,8 and opti- dures.1 With millions of proce- cal coherence tomography9 have been pro- duresI already performed in the United posed as screening tools for the detection States, the increasing popularity of laser- of previous refractive surgery. However, assisted in situ keratomileusis (LASIK) none of these instruments are readily avail- threatens the donor cornea pool. Cor- able at most eye banks. From the Division of neas that have had any previous refrac- The in vivo confocal microscope con- Ophthalmology, Department tive surgery are not suitable for transplan- sistently demonstrates the presence of vari- of Surgery, The University tation because of structural and optical able reflectivity particles in the corneal in- of New Mexico Health Sciences compromise to the tissue. Michaeli- terfaces of all patients after LASIK.10,11 Center and School of Medicine, Cohen et al2 described 2 patients who un- Pisella et al10 speculate that the highly re- and New Mexico VA Health derwent penetrating keratoplasty by sur- flective interface particles consist of me- Care System, Albuquerque geons who were unaware that the donor tallic particles originating from the mi- (Drs Mootha and Qualls); and eyes had previous LASIK. In one of these crokeratome blade and the less reflective Department of Ophthalmology cases, separation of the corneal lamellae particles may represent cellular debris or and Visual Sciences, University 11 of Wisconsin, Madison was noted at the time of surgery. plastic particles. Gokmen et al used the (Drs Dawson, Kumar, Gleiser, Eye banks rely primarily on the medi- presence of the highly reflective particles and Albert). The authors have cal and social history interview to detect found in all examined patients with the in no relevant financial interest in donors who have had previous refractive vivo confocal microscope as a basis to mea- this article. surgery. New screening techniques are re- sure the thickness of the LASIK flap. In an-

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 686

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 other recent confocal microscope study,12 highly reflective particles were found in the anterior stroma in 78 of Table 1. Demographics of Laser-assisted In Situ 85 confocal scans performed after LASIK. Like the con- Keratomileusis (LASIK) Donor Corneas and Controls focal microscope, the specular microscope is a reflected LASIK Controls P light microscope. The specular microscope is readily avail- Demographic (n = 26) (n = 26) Value* able at eye banks and is used to study the endothelial cell count density and morphologic structure in donor cor- Male/female ratio 16:10 12:14 .40 Age, mean, y 50 66 Ͻ.001 neas. This study attempted to determine the usefulness Death to preservation time, h 11.7 8.8 .10 of the specular microscope to detect the presence of the Days after death of specular 5.8 6.0 .90 highly reflective particles in the region of the central microscopy of stroma stroma corresponding to an interface in donor corneas Days after death of specular 4.8 2.5 .01 known to have had LASIK. To our knowledge, this study microscopy of endothelium is the first to examine the endothelium of donor corneas after LASIK surgery. The specular microscope was also *All t tests except for Fisher exact test of sex. used to assess central endothelial cell density and central corneal pachymetry measurements. This study also cell area ϫ100) and percentage of hexagonal cells were calcu- attempted to determine the usefulness of the slitlamp to lated by the software of the Keratoanalyzer specular micro- identify the LASIK flap edge in postmortem eyes. scope. Central pachymetry measurements were obtained on each cornea optically by focusing from the endothelium to the epi- In this study, we looked at the histologic findings thelium using the z-axis knob. The z-axis knob was used to of 11 of these LASIK donor corneas. One other histo- search for highly reflective central stromal particles starting from 13 logic study of human corneas after successful LASIK a depth of 150 µm from the endothelium. The paracentral stroma included only 4 corneas. Other reports of histologic was examined by use of the x-axis and y-axis knobs on the mi- changes in human corneas involved corneal button speci- croscope platform. The central stroma was examined at 25-µm mens after penetrating keratoplasty for LASIK-related increments toward the epithelium. The specular microscope complications14-16 or phthisical blind eyes in which the was sharply focused on any highly reflective particle in the procedure was performed just before enucleation.17 stroma, and its depth from the endothelium was noted. The maximum number of particles in any field observed was counted in each cornea. Twenty-six donor corneas already present at METHODS the New Mexico Lions Eye Bank with no known history of prior keratorefractive surgery underwent similar slitlamp examina- This project was approved by the Human Research Review Com- tion and specular microscopy to serve as controls. mittee of The University of New Mexico Health Sciences Cen- Eleven LASIK donor corneas were placed in 10% neutral ter. With use of the medical and social history interview, par- buffered formalin and processed for permanent sections. Five- ticipating eye banks of Tissue Banks International (Baltimore, micron serial sections from the center of the donor corneas were Md) identified potential donor corneas that had undergone obtained. They were examined under light microscopy (origi- LASIK. After consent for research was obtained, the corneas nal magnification, ϫ20 to ϫ400) after being stained with he- were removed by in situ excision and were placed in vials with matoxylin-eosin and periodic acid–Schiff. Optisol-GS corneal storage medium (Chiron Ophthalmics, Ir- The refractive data of the LASIK donors, including the pre- vine, Calif) by eye bank technicians using established proto- operative manifest refraction, preoperative pachymetry, date cols of the Eye Bank Association of America.18 Central endo- of LASIK, microkeratome used, footplate depth, and amount thelial cell counts were obtained by the participating eye bank of ablation, were obtained if possible. The collected data were responsible for harvesting the cornea. The corneas were sent to entered into an Excel spreadsheet (Microsoft Corp, Redmond, the New Mexico Lions Eye Bank, Albuquerque, using protocols Wash), and analyses were performed with SAS statistical soft- established by the Eye Bank Association of America.18 The do- ware, version 8.02 (SAS Institute, Cary, NC). nor corneas were stored at 4°C until further examination. Twenty-six donor corneas known to have undergone LASIK RESULTS prospectively underwent slitlamp examination with particular attention to the presence of a flap edge. A cornea fellowship– Demographic information on the LASIK donor corneas trained investigator (V.V.M.) used the slitlamp examination to and controls is given in Table 1. The mean donor age rate the LASIK flap edge as “obvious,” “subtle,” or “absent.” among the LASIK corneas (50 years) was younger than The LASIK donor corneas with an absent flap edge were con- Ͻ firmed to have had the refractive surgery by histopathologic that among the controls (66 years) (P .001). On aver- examination. These corneas then underwent thorough specu- age, specular microscopic examination of the endothe- lar microscopy with the Konan Eyebank Keratoanalyzer (Ko- lium occurred 4.8 days after death in the LASIK group nan Medical, Tokyo, Japan) with attention to the presence of compared with 2.5 days in the controls (P=.01). The avail- highly reflective particles in the region of the stroma that would able preoperative refractive and operative data on the correspond to an interface. The field of view of the specular LASIK donor corneas are given in Table 2. ϫ microscope used in this study was 0.2 0.4 mm. The vial with Slitlamp examination of the LASIK donor corneas the cornea positioned with its endothelial surface down was revealed that 12 (46%) of 26 had an obvious flap edge placed in the vial adapter and chamber holder assembly. The (Figure 1A), 10 (39%) had a subtle LASIK flap edge (Fig- z-axis knob adjustment was used to focus on the central endothelium. Endothelial cell count measurements (using the cen- ure 1B), and 4 (15%) had an absent flap edge. Among ter method technique with the built-in software of the Kera- the controls, an absent flap edge was observed in 26 toanalyzer) were obtained in each donor cornea if not obtained (100%) (PϽ.001 compared with controls, Fisher exact at the harvesting eye bank. The coefficient of variation (stan- test). Four donor corneas (15%) had evidence of infil- dard deviation of the endothelial cell area divided by the mean trates by slitlamp examination.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 687

Variable No. Mean (Range) Preoperative sphere, diopters (D) 22 −4.60 (2.25 to −10.75) Cylinder, D 22 0.87 (0.00 to 3.00) Axis,° 22 98 (0 to 178) LASIK date, months before death 22 23.1 (0.3 to 54.0) Pre-LASIK pachymetry, µm 17 564 (511 to 626) Microkeratome* footplate used, µm 18 158 (130 to 180) Stromal ablation, µm 22 47 (13 to 93)

*Microkeratomes used by surgeons included Hansatome and ACS (Bausch & Lomb Surgical, Rochester, NY), Moria CB (Moria SA, Antony, France), and SKBM (Alcon Laboratories, Fort Worth, Tex), in decreasing order of frequency.

Specular microscopy findings of the LASIK donor corneas and controls are presented in Table 3 and Table 4. The maximum number of highly reflective particles observed in any observed field in 26 LASIK donor corneas was as follows: none (0 particles), 3 (12%); mild (1-2 particles), 10 (39%); moderate (3-6 particles), 12 (46%); and severe (Ն7 particles), 1 (4%). Twenty-three (88%) of 26 LASIK donor corneas revealed highly reflective stromal particles in the region of the interface (Figure 2). Only 1 control cornea (4%) had an isolated highly reflective intrastro- A mal particle. The particles were found at a mean±SD minimal depth of 303±95 µm to a maximum depth of 362±101 µm from the endothelium. The endothelial cell density was 2138 cells/mm2 in the LASIK corneas compared with 2250 cells/mm2 in the control group (P=.39 [P=.41 adjusted for age]) (Figure 3). The coefficient of variation was 42 in the LASIK corneas and 33 in the controls (PϽ.001). The percentage of hexagonal cells was 45% in the LASIK corneas compared with 55% in the controls (P=.001) (Table 3). The mean central pachymetry mea- surement was 506 µm in the LASIK group compared with 528 µm in the control group (P=.06). Histopathologic results are summarized in Table 5. Pathological findings confirmed the presence of a lamellar flap in all examined LASIK donor corneas. All interface scars showed vacuolization and pyknosis of keratocytes along the lamellar cut (Figure 4). Metallic particles were not found on the serial sections taken from the center of the donor corneas in any of the examined interfaces. Epithelial facets (minor epithelial down-growth) were occasionally seen at the entrance to the lamellar cut. Three of the 4 donor corneas that had peripheral infiltrates had evidence of nongranulomatous inflammatory anterior stromal infiltrates. One cornea stained for gram-positive cocci on the surface epithelium by Brown-Brenn stain and another cornea with Gomori methenamine silver stained positive for a small number of yeast organisms on the surface epithelium. The endothelium was unremarkable in all ex-

amined cases except for 1 pair of donor corneas with de- B creased numbers of endothelial cells. Figure 1. A, Slitlamp photograph of donor cornea with epithelial side down in a vial with Optisol-GS. Retroillumination reveals a laser-assisted in situ COMMENT keratomileusis (LASIK) flap edge rated as “obvious.” Cornea is from a 54-year-old female donor with LASIK performed 41⁄2 years before death. Until better screening technology is developed and imple- B, An example of a “subtle” LASIK flap edge by slitlamp examination from a mented by eye banks, the slitlamp and specular micro- 60-year-old male donor who had the procedure 21⁄2 years before death.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 688

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 Table 3. Specular Microscopy Results* Table 4. Highly Reflective Intrastromal Particles in 26 Laser-assisted In Situ Keratomileusis Donor Corneas LASIK Controls P Finding (n = 26) (n = 26) Value† Finding Mean ± SD (Range) Presence of highly reflective stromal 23 (88) 1 (4) Ͻ.001 Maximum particles in any observed field 3.00 ± 2.56 (0-13) particles Depth from endothelium, µm Presence of less reflective stromal 2 (8) 4 (15) .67 Minimum 303 ± 95 (145-539) particles Maximum 362 ± 101 (167-558) Presence of clear stroma 1 (4) 21 (81) Ͻ.001 Endothelial cell density, cell/mm2 2138 2250 .39 Coefficient of variation 42 33 Ͻ.001 Percentage of hexagonal cells, % 45 55 .001 Pachymetry, mean ± SD, µm 506 ± 80 528 ± 51 .06

*Data are number (percentage) unless otherwise indicated. †Comparison of laser-assisted in situ keratomileusis (LASIK) donor cornea with controls, Fisher exact test for binary data and t tests for continuous data.

Figure 3. A, Specular micrograph of endothelium from a 46-year-old laser-assisted in situ keratomileusis (LASIK) donor cornea 1 day after death. Cell density and morphologic structure appear normal. B, Specular micrograph of a 45-year-old LASIK donor cornea endothelium 5 days after death. Moderate and diffuse changes are found in cell appearance and morphologic structure, with notable distortion of hexagonal shape and scattered areas of blackening consistent with endothelial cell edema.

Figure 2. A, Specular microscopy image focused 255 µm from the 26) of the LASIK donor corneas had a subtle flap edge endothelium reveals a severe amount of highly reflective stromal particles. and 15% (4/26) had no detectable flap edge; these would This 47-year-old donor cornea underwent laser-assisted in situ probably be missed by routine slitlamp examination. Eye keratomileusis (LASIK) 9 months before death. The field of view is 0.2ϫ0.4 bank technicians, however, must be trained to recog- mm. B, A more representative specular micrograph of highly reflective stromal particles. The maximum number of highly reflective particles nize a LASIK flap edge, as nearly half of LASIK donor cor- observed was 3 particles, found a distance of 489 µm from the endothelium. neas could be potentially screened by the simple use of This 47-year-old donor had LASIK 2 years before death. The particles range the slitlamp. Retroillumination slitlamp techniques are in size from approximately 5 to 20 µm. useful in the detection of a LASIK flap. In this study, clear cornea cataract wounds, astigmatic keratotomy scars, ar- scope may be useful in the detection of donor corneas cus senilis changes, and posterior embryotoxon changes with previous LASIK surgery. The results of this study were seen that could mimic a LASIK flap to an inexpe- suggest that 46% (12/26) of LASIK donor corneas have rienced slitlamp observer. Careful slitlamp examination an obvious flap edge. In this unmasked study, 39% (10/ of the endothelial surface can help distinguish a clear cor-

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 689

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 Table 5. Histopathologic Findings of Donor Corneas After Laser-assisted In Situ Keratomileusis (LASIK)

Donor Age/Sex

Finding 54/F*† 61/M 29/F* 51/F* 22/M 22/M 46/M*

Time after LASIK 41⁄2 y Unknown 10 mo and 1 y 1 y 9 d 9 d 31⁄2 y Postmortem delay to 8 3 11 12 6 6 3 formalin (in Optisol-GS), d Epithelial facets Present Absent Present Absent Present Absent Present Vacuolization and Present Present Present Present Present Present Present pyknosis of keratocytes Interface debris Absent Absent Absent Absent Inflammatory cells Inflammatory cells Absent Infiltrates Absent Chronic Absent Absent Erosion of Erosion of Absent nongranulomatous epithelium and epithelium and inflammation in small, chronic moderate anterior stroma nongranuloma- nongranuloma- peripheral to lamellar tous anterior tous anterior cut and gram-positive stromal infiltrate, stromal infiltrate, cocci with no with yeast organisms seen Endothelium Unremarkable† Unremarkable Unremarkable Unremarkable Unremarkable Unremarkable Decreased endothelial cells

*Donor pair of corneas. †80% Deep vertical scars and previous astigmatic keratotomy.

nea cataract wound and posterior embryotoxon from a resolution of standard eye bank specular microscopes is true microkeratome-induced flap edge. far less. In our study, we were probably detecting only a In this study, 15% (4/26) of the LASIK donor cor- small number of the most highly reflective of the vari- neas were noted to have infiltrates by slitlamp examina- able reflectivity particles seen in vivo by the confocal tion, suggesting that the well-documented neuro- microscope. The poorer resolution of the specular mi- trophic status of the cornea following LASIK19 may further croscope may also account for why 12% (3/26) of the predispose to exposure-related keratitis in intubated or LASIK donor corneas had no detectable highly reflec- sedated patients. The details of these 4 cases will be pub- tive stromal particles, despite a thorough search. Also, lished in a separate article. the eye bank specular microscope used in this study The results of this study suggest that the standard was designed for examination of a small area of the cen- specular microscope available in eye banks can detect tral corneal endothelium (0.2ϫ0.4 mm) and may miss highly reflective intrastromal particles in donor corneas peripheral interface particles in a typical 8- or 9-mm after LASIK. In published reports using the in vivo con- LASIK flap. focal microscope, the presence of highly reflective inter- Specular microscope reflectivity is a function of a face particles varies between 92%12 and 100%10,11 in pa- change in index of refraction at a particular interface in tients after LASIK. In our study, specular microscopy the tissue examined. Air bubbles on the corneal surface, revealed highly reflective stromal particles in 88% (23/ the interface between the epithelium and corneal stor- 26) of the LASIK donor corneas. The stromal depth of age medium, and epithelial irregularities or debris may the particles correlates to where microkeratome- induce specular reflectivity. Care must be taken not to induced changes would be seen. mistake these artifacts for highly reflective particles within The mean±SD density of variable reflectivity par- the substance of the stroma seen at the LASIK interface. ticles (all particles, including highly reflective and less Less reflective stromal debris is not a reliable indicator reflective) at the interface by in vivo confocal micros- of a microkeratome cut, as this was occasionally seen in copy has been reported to be 504±101 particles/mm2 at the control corneas. Interestingly, we cannot account for 8 days after the LASIK procedure and decreases during the presence of a single, highly reflective particle in the the first 3 months after surgery to stabilize at 332±100 stroma of a control cornea from a 70-year-old female do- particles/mm2.10 Another in vivo confocal microscope nor who died of cancer. The fellow cornea from this pa- study12 reported the mean±SD density of the highly re- tient had a few highly reflective particles at the level of flective particles at the interface to be 19.8±24.6 particles/ the epithelium. mm2 at 1 week after the LASIK procedure and did not In addition to evaluating the donor cornea endo- change significantly with time. In our investigations with thelium, the specular microscope may be a useful in- the specular microscope, density measurements of the strument to screen for previous LASIK surgery by the highly reflective particles were not performed. How- detection of the highly reflective stromal particles cor- ever, the maximum number of highly reflective par- responding to the interface. However, the manual search ticles in any observed field (0.08 mm2) averaged only 3 for highly reflective stromal particles can be tedious, as particles. In comparison to the confocal microscope, the 50% (13/26) of the LASIK donor corneas had a mild

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 690

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 amount of particles or none. Masked studies are required to determine the true sensitivity and specificity of existing specular microscopes to screen for donor corneas that have had LASIK. The results of this study suggest that the detection of highly reflective interface debris may form an effective basis for screening using existing specular microscopes until better screening tech- nologies are developed. In vivo specular microscopic investigations in patients who have had LASIK have demonstrated no significant change in central endothelial cell counts.20 How- ever, a study21 reported a transient endothelial dysfunction marked by increased pleomorphism with definite loss of hexagonality immediately after LASIK surgery. In our study, the mean central endothelial cell count density was slightly lower in the LASIK group (2138 cells/mm2) compared with the control donor corneas (2250 cells/mm2). This small difference was, however, not statistically significant even when the age discrepancy in the 2 groups was considered (P=.39 [P=.41 adjusted for age]). How- ever, the coefficient of variation (indicator of polymega- thism) was slightly higher in the LASIK group at 42 compared with 33 in the controls (PϽ.001). The percentage of hexagonal cells (indicator of pleomorphism) was slightly lower in the LASIK group (45%) compared with the controls (55%) (P=.001). On average, the endothelium was analyzed with the specular microscope 4.8 days after death in the LASIK donor corneas compared with 2.5 days in the controls (P=.01). This 2-day delay was attributable to the processing and shipping time required to send the tissue from participating eye banks to the New Mexico Lions Eye Bank. This project was designed primarily for the specular microscopic examina- Figure 4. Example of pyknosis and vacuolization of keratocytes in corneal tion of the stroma in donor corneas. Further studies with interface (hematoxylin-eosin, original magnification ϫ400). proper matching of age, death to preservation time, and delay before specular microscopy of the endothelium are the decreased keratocyte density in the stroma adjacent required to assess the effects of LASIK surgery on cen- to the LASIK lamellar cut demonstrated by the in vivo tral endothelial cell count density, morphologic struc- confocal microscope.12 Further research is required to elu- ture, and viability. cidate the nature and clinical significance of the kerato- Although the LASIK donor corneas were slightly cyte changes. thinner (506 µm) compared with the control corneas (528 µm), this difference was not statistically significant Submitted for publication February 3, 2003; final revision (P=.06). Pachymetry measurements with use of specu- received September 24, 2003; accepted November 21, 2003. lar microscopy may not be as reliable as ultrasound tech- This project was supported in part by the Dedicated nology. However, the pachymetry results in this study Health Research Funds of The University of New Mexico and the potential artifacts induced by epithelial defects School of Medicine, Albuquerque. and variable stromal edema of corneas in the storage me- The study was presented in part at the 40th Annual Sci- dia suggest that pachymetry using specular microscopy entific Session of Eye Bank Association of America; Novem- may not be an effective basis for screening for previous ber 10, 2001; New Orleans, La; and the 41st Annual Meet- LASIK surgery. ing of the Eye Bank of Association of America; June 22, 2002; The histologic findings on the LASIK donor cor- Ponte Vedra Beach, Fla. neas failed to identify metallic particles in any of the in- We thank Tissue Banks International, Kestrel Corpo- terfaces examined to be the source of the highly reflec- ration, Albuquerque, Gregory S. H. Ogawa, MD, and Curt tive particles seen by specular and confocal microscopy. Vavra, RN, for the collection of donor corneas. We also thank However, the consistent histopathologic finding of vacu- Edward Otero and Chris Miguel-Nathan for their assis- olization and pyknosis of keratocytes along the lamellar tance with preparation of the manuscript. cut may account for some of the variable reflectivity par- Corresponding author and reprints: V. Vinod Mootha, ticles seen by confocal and specular microscopy. The pyk- MD, Division of Ophthalmology, Department of Surgery, notic nuclei may be related to the previous LASIK sur- The University of New Mexico Health Sciences Center and gery, but postmortem changes cannot be ruled out. School of Medicine, 2211 Lomas Blvd NE, 2-Ambulatory Vacuolization and pyknosis of keratocytes have been con- Care Center, Albuquerque, NM 87131 (e-mail: vmootha firmed by other histologic studies13 and may account for @salud.unm.edu).

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 691

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 11. Gokmen F, Jester JV, Petroll WM, McCulley JP, Cavanagh HD. In vivo confocal REFERENCES microscopy through-focusing to measure corneal flap thickness after laser in situ keratomileusis. J Cataract Refract Surg. 2002;28:962-970. 1. Eye Bank Association of America. Annual Statistical Report. Washington, DC: Eye 12. Mitooka K, Ramirez M, Maguire L, et al. Keratocyte density of central human cor- Bank Association of America; 2001. nea after laser in situ keratomileusis. Am J Ophthalmol. 2002;133:307-314. 2. Michaeli-Cohen A, Lambat AL, Loloma F, Rootman DS. Two cases of a penetrat- 13. Anderson NJ, Edelhauser HF, Sharara N, et al. Histologic and ultrastructural finding keratoplasty with tissue from a donor who had undergone LASIK surgery. ings in human corneas after successful laser in situ keratomileusis. Arch Oph- Cornea. 2002;21:111-113. thalmol. 2002;120:288-293. 3. Ousley PJ, Terry MA. Objective screening methods for prior refractive surgery 14. Wright JD Jr, Neubaur CC, Stevens G Jr. Epithelial ingrowth in a corneal graft in donor tissue. Cornea. 2002;21:181-188. treated by laser in situ keratomileusis: light and electron microscopy. J Cataract 4. Ousley PJ, Terry MA. Use of portable topography machine for screening donor Refract Surg. 2000;26:49-55. tissue for prior refractive surgery. Cornea. 2002;21:745-750. 15. Jabbur NS, Stark WJ, Green WR. Corneal ectasia after laser-assisted in situ ker- 5. Lim-Bon-Siong R, Williams JM, Samapungphong S, Chuck RS, Pepose JS. Screen- atomileusis. Arch Ophthalmol. 2001;119:1714-1716. ing of myopic photorefractive keratectomy in eye bank eyes by computerized vid- 16. Geggel HS, Talley AR. Delayed onset keratectasia following laser in situ ker- eokeratography. Arch Ophthalmol. 1998;116:617-623. atomileusis. J Cataract Refract Surg. 1999;25:582-586. 6. Stoiber J, Ruckhofer J, Hitzl W, Grabner G. Evaluation of donor tissue with a new 17. Latval T, Barraquer-Coll C, Tervo K, Tervo T. Corneal wound healing and nerve video keratoscope: the Keratron Scout. Cornea. 2001;20:859-863. morphology after excimer laser in situ keratomileusis in human eyes. J Refract 7. Merin LM, Brown MF, Howdeshell LL. Darkfield biomicrography of eye bank do- Surg. 1996;12:677-683. nor corneas. Cornea. 2001;20:210-213. 18. Eye Bank Association of America. Procedures Manual. Washington, DC: Eye Bank 8. Ogawa GSH, Truit PW, Otten LJ, Soliz P, Erry G, Nemeth SC. Donor cornea char- Association of America; October 2001. acterization utilizing distorted grating-based wavefront analysis [abstract]. In- 19. Battat L, Macri A, Durson D, Plugfelder SC. Effects of laser in situ keratomileusis vest Ophthalmol Vis Sci. 2001;42(suppl):S898. on tear production, clearance, and the ocular surface. Ophthalmology. 2001; 9. Priglinger SG, Neubauer AS, May CA, et al. Optical coherence tomography for 108:1230-1235. the detection of laser in situ keratomileusis in donor cornea. Cornea. 2003;22: 20. Perez-Santonja JJ, Sakla HF, Gobbi F, Alio JL. Corneal endothelial changes after 46-50. laser in situ keratomileusis. J Cataract Refract Surg. 1997;23:177-183. 10. Pisella PJ, Auzerie O, Bokobza Y, Debbasch C, Bandouin C. Evaluation of cor- 21. Kim T, Sorenson AL, Krishnaswamy S, Carlson AN, Edelhauser HF. Acute corneal stromal changes in vivo after laser in situ keratomileusis with confocal mi- neal endothelial changes after laser in situ keratomileusis. Cornea. 2001;20:597- croscopy. Ophthalmology. 2001;108:1744-1750. 602.

.؋3. Created by Patrick J. Saine, MEd, CRA, Dartmouth-Hitchcock Medical School, Lebanon, NH 3

(REPRINTED) ARCH OPHTHALMOL / VOL 122, MAY 2004 WWW.ARCHOPHTHALMOL.COM 692