Ocular Integrity After Anterior Ciliary Sclerotomy and Scleral Ablation by the Er:YAG Laser

PURPOSE

To establish the risk of ocular rupture after proposed surgical reversal of presbyopia by anterior ciliary sclerotomy (ACS) or by the Er:YAG laser (HOYA Continuum, Tokyo, Japan).

METHODS

A total of 45 pig eyes (15 control eyes) were examined. Fifteen eyes were placed into one of two study groups and another 15 eyes were used as controls. One group underwent scleral incisions with the use of a diamond knife, and the other group underwent Er:YAG laser scleral incisions. In both study groups, 8 radial incisions, 2 parallel cuts each at 4 quadrants, 2 mm apart, 4 mm long, and starting 2 mm away from the limbus, were made. A 3-kg steel weight was released from a measured height to the pig's eye, and ocular rupture energy (joules) was measured.

RESULTS

The mean rupture energy was 26.0 J for control eyes, 15.7 J for the ACS eyes, and 12.2 J for the Er:YAG laser eyes. The ACS and the Er:YAG laser eyes ruptured at significantly lower energies (ACS, P < .001; Er:YAG, P < .001) than the control eyes. Comparison of the ACS group and the Er:YAG laser group showed no statistically significant difference (P = .052) in rupture energy.

CONCLUSIONS

Scleral incisions by ACS and the Er:YAG laser significantly weakened ocular integrity compared with control eyes. Any patients undergoing ACS or Er:YAG laser scleral incision should be informed of the attendant potential risk after ocular trauma.

Rupture of Radial Keratotomy Incisions by Blunt Trauma 6 Years After Combined Photorefractive Keratectomy/Radial Keratotomy

PURPOSE

To report a case of traumatic corneal rupture that occurred 6 years previous, following combined radial keratotomy (RK) and photorefractive keratectomy (PRK).

METHODS

A 28-year-old man experienced a severe direct trauma to the right eye. Upon initial examination, a ruptured globe was diagnosed. Four of the eight radial incisions were ruptured with extrusion of intraocular tissues. The patient was also diagnosed with a fracture of the medial wall of the right orbit. The patient received immediate surgery during which the radial incisions that had been torn were stitched with a suture.

RESULTS

Following the postoperative period, the patient had visual acuity of light perception.

CONCLUSION

PRK, carried out on a cornea already treated with RK, may increase the likelihood of rupture in blunt trauma.

Dehiscence of Radial Keratotomy Wounds Without Globe Rupture Following Explosion Injury

PURPOSE

To report a case of explosive trauma to a patient with a history of radial keratotomy (RK), which resulted in multiple wound dehiscences but not globe rupture.

METHODS

A 29-year-old male underwent radial keratotomy 1 year before he sustained facial trauma from a gasoline tank explosion. Corneal abrasions were treated with copious irrigation, topical antibiotics, corticosteroids, and scopolamine. He did not have a ruptured globe in either eye.

RESULTS

The incision sites from radial keratotomy had evidence of anterior dehiscence in both eyes. One month following the injury, the patient had corrected visual acuity of 20/20-1 in the right eye and 20/25+1 in the left eye. At that time, the RK wounds were well healed with minimal irregularity over the incision sites.

CONCLUSION

This case demonstrates the excellent recovery of visual acuity in a patient with a partial thickness traumatic wound rupture 12 months following radial keratotomy.

Immunohistochemical Study of Subepithelial Haze After Phototherapeutic Keratectomy

PURPOSE

Subepithelial haze is a frequent complication and is often the cause of regression after photorefractive keratectomy (PRK). The lack of understanding of this undesirable complication following PRK is in part due to the limited availability of suitable tissues for pathological studies.

METHODS

We examined the expression of various extracellular components in the cornea of a 46-year-old man who underwent phototherapeutic keratectomy (PTK) to remove a central corneal scar secondary to trauma. The patient subsequently underwent penetrating keratoplasty. A scar-free region containing an area of slight subepithelial haze adjacent to normal cornea was used for immunohistochemical staining with antibodies directed against cytoskeletal proteins, ie, vimentin, desmin and smooth muscle actin, and the extracellular components, laminin, heparan sulfate, keratan sulfate, and collagen types III, IV, V, and VII.

RESULTS

Immunohistochemistry revealed that basal epithelial cells expressed components of basement membrane. The stromal fibroblasts within the haze tissue were labeled by anti-smooth muscle actin antibodies, a characteristic of myofibroblasts, which synthesized and secreted extracellular matrix components that contributed to the formation of the disorganized collagenous matrix and may account for subepithelial haze.

CONCLUSIONS

The expression patterns for the cytoskeletal proteins and extracellular components indicated that the formation of subepithelial haze is a process of tissue remodeling, involving both corneal basal epithelial cells and keratocytes during wound repair.

Assessment of Corneal Wound Healing by Interactive Topography

INTRODUCTION

Constitutive properties of the cornea and wounds within the cornea have been measured previously by destructive methods in which a strip of cornea was removed, placed on an instrument, and stretched until broken. To assess corneal wound healing and the interaction of medication, incision patterns and other clinical issues, we present a simple, noninvasive test of corneal wound healing utilizing a videokeratoscope and Honan balloon.

METHODS

A pre-test corneal topography was performed. The Honan balloon was placed on the eye at a pressure of 30mm mercury for 5 minutes. After removal of the balloon, additional corneal topographies were performed for comparison to the baseline topography. Study eyes were divided into six groups: 15 eyes in the normal group not involved in the Honan balloon test, 15 eyes formed a control group without previous ocular surgery, 15 eyes were within 3 months of radial keratotomy (RK), 15 eyes were more than 9 months after RK, 12 eyes had previous automated in situ keratomileusis (ALK), and 12 eyes had previous penetrating keratoplasty (PK).

RESULTS

Average videokeratometric flattening was reported for all groups at intervals of 1, 2, and 3 minutes after removal of the Honan balloon. The normal group flattened by 0.04 +/- 0.10 D (range, +0.10 to -0.12 D) at 1 minute; 0.02 +/- 0.08 D (range, +0.10 to -0.10 D) at 2 minutes; and 0.02 +/- 0.06 D (range, +0.10 to -0.09 D) at 3 minutes. The control group flattened by -0.10 +/- 0.10 D (range, +0.30 to -0.30 D) at 1 minute; 0.01 +/- 0.12 D (range, +0.15 to -0.25 D) at 2 minutes; and 0.07 +/- 0.11 D (range, +0.14 to -0.18 D) at 3 minutes. The 3-month RK group flattened 0.95 +/- 0.23 D (range, 1.35 to 0.67 D) at 1 minute; 0.53 +/- 0.16 D (range, 0.71 to 0.39 D) at 2 minutes; and 0.40 +/- 0.15 D (range, 0.56 to 0.30 D) at 3 minutes. The 9-month RK group flattened 0.10 +/- 0.13 D (range, 0.23 to 0.02 D) at 1 minute; 0.10 +/- 0.12 D (range, 0.18 to -0.01 D) at 2 minutes; and 0.01 +/- 0.14 D (range 0.05 to 0.10 D) at 3 minutes. The ALK group flattened 0.65 +/- 0.42 D (range 0.98 to 0.38 D) at 1 minute; 0.27 +/- 0.19 D (range 0.39 to 0.10 D) at 2 minutes; and 0.21 +/- 0.17 D (range, 0.29 to 0.09 D) at 3 minutes. The PK group flattened 1.30 +/- 0.60 D (range, 1.75 to 0.90 D) at 1 minute; 1.18 +/- 0.43 D (range, 1.51 to 0.98 D) at 2 minutes; and 0.41 +/- 0.57 D (range, 0.88 to 0.30 D) at 3 minutes.

CONCLUSIONS

We have established normal corneal wound healing curves from preliminary data utilizing Buzard interactive topography on normal control eyes and after radial keratotomy, automated lamellar keratoplasty, and penetrating keratoplasty. Deviation from these normal curves indicates either excessive or inadequate wound healing.