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Second Opinion on Brevital
letters Corneal Subepithelial Infiltrates Following Photorefractive Keratectomy
W
e would like to commend Teal and coauthors I on their recent article. Through their survey of Canadian ophthalmologists, they have described a relatively rare and important complication following photorefractive keratectomy (PRK) . Our experience in the treatment and prevention of these infiltrates has provided some additional, useful information. When a corneal infiltrate is encountered following PRK, the etiology is inflammatory, infectious, or both. Since an infectious corneal ulcer is the most serious early PRK complication, physicians will be tempted to initiate the standard corneal ulcer therapy of fortified antibiotics every hour around the clock. While this treatment will certainly sterilize the cornea, it will also eliminate most of the healing epithelium and could provide toxic irritation to the freshly ablated stromal surface. Delayed corneal re-epithelialization can result in diffuse stromal haze and myopic regression with a poor refractive result. 2 We have found that the reduced epithelial toxicity of topical fluoroquinolones provides for good epithelial healing when treating a corneal infiltrate if used in conjunction with frequent lubrication. Since topical ciprofloxacin 0.3% has been associated with white crystalline corneal precipitates in 23.7% of cases,3 we prefer to use topical ocufloxacin 0.3%. A recent study has indicated that topical ocufloxacin is as efficacious as fortified antibiotics in the treatment of corneal ulcers and has fewer ocular toxic effects. 4 Generally, topical steroids are discontinued when a corneal ulcer is identified. However, in the case of the inflammatory subepithelial infiltrates following PRK, it is important not to stop topical corticosteroid therapy, as it is necessary to reduce the stromal influx of polymorphonuclear cells that can potentially result in a stromal melt. l We suggest reducing topical steroid use to twice a day during the initial treatment of the corneal infiltrate. Obviously, patients must be monitored daily while on the topical corticosteroids. If there is any indication of
an infectious etiology to the corneal infiltrate, the corticosteroids should be discontinued. Finally, it is thought that corneal infiltrates following PRK may be related either to contact lenses or to the topical nonsteroidal anti-inflammatory drugs (NSAIDs) used for postoperative pain control. Indeed, Teal and coauthors I have pointed out that this complication was first noted when topical NSAIDs were introduced following PRK. For this reason, we have reduced our dose of topical NSAIDs by half-to twice a day for 3 days following PRK. This provides a similar degree of pain relief as the four drops per day schedule we were previously using and should significantly reduce the incidence of this complication. LOUIS
E. PROBST V, MD
J EFFERY J. MACHAT, MD
Windsor, Canada References I . Teal P, Breslin C, ArshinoffS, Edmison D. Corneal subepithelial infiltrates following excimer laser photorefractive keratectomy. J Cataract Refract Surg 1995; 21:516-518 2. Ditzen K, Anschutz T, Schroder E. Photorefractive keratectomy to treat low, medium, and high myopia: a multicenter study. J Cataract Refract Surg 1994; 20:234-238 3. Leibowitz HM. Clinical evaluation of ciproRoxacin 0.3% ophthalmic solution for treatment of bacterial keratitis. Am J Ophthai mol 1991; 112(suppl):34S-47S 4. O'Brien TP, Maguire MG, Fink NE, et al. Efficacy of oRoxacin vs cefazolin and tobramycin in the therapy for bacterial keratitis. Arch Ophthalmol1995; 113:1257-1265
Second Opinion on Brevital
I
n his article "Drop, Then Decide Approach to Topical Anesthesia," I Dinsmore dismisses the use of methohexital sodium (Brevital®) as irrelevant to considerations of intravenous sedation for cataract surgery and cites the "possibility of hiccups or involuntary muscle movements." Brevital is a drug with a long track record of safety and efficacy, with minimal side effects. It does not cause amnesia, prolonged somnolence, or late confusion and is the most inexpensive intravenous agent available for sedation. Anecdotally, in approximately 10,000 cases over more than a decade, I have seen one case of hiccups,
J CATARACT REFRACT SURG-VOL 22. APRIL 1996
281
LETTERS
which did not interfere with the procedure because the hiccups subsided spontaneously. Any involuntary muscle movements resolve within 1 or 2 minutes following onset, as the sedation wears off. 1 have no idea why Brevital routinely gets only disrespect as an intravenous sedative for patients of all ages having cataract surgery. Many anesthesiologists dismiss it, preferring midazolam (Versed®), diprivan (Propifal®) , and even thiopental (Pentothal®). 1 have found that Brevital alone rarely if ever causes snoring, confusion, or unwanted side effects. 1 commend its use to those who are interested in avoiding the superstitions that have been wrongly attached to this ultrashort-acting barbiturate. SAMUAL
M. SALAMON, MD
Cleveland, Ohio Reference
1. Dinsmore Sc. Drop, then decide approach to topical anesthesia. ] Cataract Refract Surg 1995; 21:666-671
Passport System Cutting of a Chiron CIO VB Silicone Lens
U
se of foldable intraocular lenses (10Ls) is increasing in the United States as well as in Europe and Japan. The majority of these foldable lenses have been silicone. Injector systems have also become extremely popular, often allowing insertion through smaller wounds than otherwise possible with foldable 10Ls. One new system that is being used by many ophthalmologists is the Passport system (Chiron), which allows easy loading and injection, certainly through incisions of 3.0 mm and smaller. 1 would like to report a complication with such an injector. During an uncomplicated surgery, a 22 diopter Chiron CI0 UB silicone IOL was injected into the eye with the Passport system. Loading proceeded without difficulty, and there was no difficulty starting the lens down the injector port. As the lens started to fold in the injector tube and was part way down the port starting into the eye, the tube suddenly cracked in multiple
282
places and the lens explosively entered the eye. The Passport system was removed and the lens easily inserted into the capsular bag. Although the tube was still intact, it was cracked in multiple places with many uneven pieces. For this reason, the eye was carefully inspected with the operating microscope at high magnification to ascertain whether any pieces of the tube had been dislodged into the eye. Although no such pieces could be found, it was obvious that there was, along the superior part of the optic approximately 1.0 mm from the edge, a deep gash in the silicone IOL material. At the time, it was decided that the rest of the optic was unaffected and that removal of the lens would create greater morbidity than leaving it in place. It was rotated until the gash was superior and well under the capsulorhexis edge. The wound was self-sealing, and there were no other difficulties. On the first postoperative day, vision was excellent and the eye had minimal inflammation. However, slitlamp examination revealed that the cut into the silicone material extended at least halfway through the optic. The patient has experienced no complications or problems associated with this. Although this particular incident did not create any difficulty for the patient, it is obvious that the tube material could not withstand the pressure of compressing the silicone material and suddenly shattered. Such scoring and cutting of the lens material could easily have occurred more centrally in the optic, rendering the lens optically inadequate. This would have required removal and replacement, which is not a simple matter with small incision surgery. A greater concern and complication would have been dislodgement or insertion of small fragments of tube material into the eye. Although the tube was shattered, all the pieces held together. While my experience with the Passport system is relatively minimal, I have seen another case in which the lens broke out of the tube before entering the eye. The tube is suspect in my mind.
J CATARACT REFRACT SURG-VOL 22, APRIL 1996
RANDALL]. OLSON,
MD
Salt Lake City, Utah
W
e would like to commend Teal and coauthors I on their recent article. Through their survey of Canadian ophthalmologists, they have described a relatively rare and important complication following photorefractive keratectomy (PRK) . Our experience in the treatment and prevention of these infiltrates has provided some additional, useful information. When a corneal infiltrate is encountered following PRK, the etiology is inflammatory, infectious, or both. Since an infectious corneal ulcer is the most serious early PRK complication, physicians will be tempted to initiate the standard corneal ulcer therapy of fortified antibiotics every hour around the clock. While this treatment will certainly sterilize the cornea, it will also eliminate most of the healing epithelium and could provide toxic irritation to the freshly ablated stromal surface. Delayed corneal re-epithelialization can result in diffuse stromal haze and myopic regression with a poor refractive result. 2 We have found that the reduced epithelial toxicity of topical fluoroquinolones provides for good epithelial healing when treating a corneal infiltrate if used in conjunction with frequent lubrication. Since topical ciprofloxacin 0.3% has been associated with white crystalline corneal precipitates in 23.7% of cases,3 we prefer to use topical ocufloxacin 0.3%. A recent study has indicated that topical ocufloxacin is as efficacious as fortified antibiotics in the treatment of corneal ulcers and has fewer ocular toxic effects. 4 Generally, topical steroids are discontinued when a corneal ulcer is identified. However, in the case of the inflammatory subepithelial infiltrates following PRK, it is important not to stop topical corticosteroid therapy, as it is necessary to reduce the stromal influx of polymorphonuclear cells that can potentially result in a stromal melt. l We suggest reducing topical steroid use to twice a day during the initial treatment of the corneal infiltrate. Obviously, patients must be monitored daily while on the topical corticosteroids. If there is any indication of
an infectious etiology to the corneal infiltrate, the corticosteroids should be discontinued. Finally, it is thought that corneal infiltrates following PRK may be related either to contact lenses or to the topical nonsteroidal anti-inflammatory drugs (NSAIDs) used for postoperative pain control. Indeed, Teal and coauthors I have pointed out that this complication was first noted when topical NSAIDs were introduced following PRK. For this reason, we have reduced our dose of topical NSAIDs by half-to twice a day for 3 days following PRK. This provides a similar degree of pain relief as the four drops per day schedule we were previously using and should significantly reduce the incidence of this complication. LOUIS
E. PROBST V, MD
J EFFERY J. MACHAT, MD
Windsor, Canada References I . Teal P, Breslin C, ArshinoffS, Edmison D. Corneal subepithelial infiltrates following excimer laser photorefractive keratectomy. J Cataract Refract Surg 1995; 21:516-518 2. Ditzen K, Anschutz T, Schroder E. Photorefractive keratectomy to treat low, medium, and high myopia: a multicenter study. J Cataract Refract Surg 1994; 20:234-238 3. Leibowitz HM. Clinical evaluation of ciproRoxacin 0.3% ophthalmic solution for treatment of bacterial keratitis. Am J Ophthai mol 1991; 112(suppl):34S-47S 4. O'Brien TP, Maguire MG, Fink NE, et al. Efficacy of oRoxacin vs cefazolin and tobramycin in the therapy for bacterial keratitis. Arch Ophthalmol1995; 113:1257-1265
Second Opinion on Brevital
I
n his article "Drop, Then Decide Approach to Topical Anesthesia," I Dinsmore dismisses the use of methohexital sodium (Brevital®) as irrelevant to considerations of intravenous sedation for cataract surgery and cites the "possibility of hiccups or involuntary muscle movements." Brevital is a drug with a long track record of safety and efficacy, with minimal side effects. It does not cause amnesia, prolonged somnolence, or late confusion and is the most inexpensive intravenous agent available for sedation. Anecdotally, in approximately 10,000 cases over more than a decade, I have seen one case of hiccups,
J CATARACT REFRACT SURG-VOL 22. APRIL 1996
281
LETTERS
which did not interfere with the procedure because the hiccups subsided spontaneously. Any involuntary muscle movements resolve within 1 or 2 minutes following onset, as the sedation wears off. 1 have no idea why Brevital routinely gets only disrespect as an intravenous sedative for patients of all ages having cataract surgery. Many anesthesiologists dismiss it, preferring midazolam (Versed®), diprivan (Propifal®) , and even thiopental (Pentothal®). 1 have found that Brevital alone rarely if ever causes snoring, confusion, or unwanted side effects. 1 commend its use to those who are interested in avoiding the superstitions that have been wrongly attached to this ultrashort-acting barbiturate. SAMUAL
M. SALAMON, MD
Cleveland, Ohio Reference
1. Dinsmore Sc. Drop, then decide approach to topical anesthesia. ] Cataract Refract Surg 1995; 21:666-671
Passport System Cutting of a Chiron CIO VB Silicone Lens
U
se of foldable intraocular lenses (10Ls) is increasing in the United States as well as in Europe and Japan. The majority of these foldable lenses have been silicone. Injector systems have also become extremely popular, often allowing insertion through smaller wounds than otherwise possible with foldable 10Ls. One new system that is being used by many ophthalmologists is the Passport system (Chiron), which allows easy loading and injection, certainly through incisions of 3.0 mm and smaller. 1 would like to report a complication with such an injector. During an uncomplicated surgery, a 22 diopter Chiron CI0 UB silicone IOL was injected into the eye with the Passport system. Loading proceeded without difficulty, and there was no difficulty starting the lens down the injector port. As the lens started to fold in the injector tube and was part way down the port starting into the eye, the tube suddenly cracked in multiple
282
places and the lens explosively entered the eye. The Passport system was removed and the lens easily inserted into the capsular bag. Although the tube was still intact, it was cracked in multiple places with many uneven pieces. For this reason, the eye was carefully inspected with the operating microscope at high magnification to ascertain whether any pieces of the tube had been dislodged into the eye. Although no such pieces could be found, it was obvious that there was, along the superior part of the optic approximately 1.0 mm from the edge, a deep gash in the silicone IOL material. At the time, it was decided that the rest of the optic was unaffected and that removal of the lens would create greater morbidity than leaving it in place. It was rotated until the gash was superior and well under the capsulorhexis edge. The wound was self-sealing, and there were no other difficulties. On the first postoperative day, vision was excellent and the eye had minimal inflammation. However, slitlamp examination revealed that the cut into the silicone material extended at least halfway through the optic. The patient has experienced no complications or problems associated with this. Although this particular incident did not create any difficulty for the patient, it is obvious that the tube material could not withstand the pressure of compressing the silicone material and suddenly shattered. Such scoring and cutting of the lens material could easily have occurred more centrally in the optic, rendering the lens optically inadequate. This would have required removal and replacement, which is not a simple matter with small incision surgery. A greater concern and complication would have been dislodgement or insertion of small fragments of tube material into the eye. Although the tube was shattered, all the pieces held together. While my experience with the Passport system is relatively minimal, I have seen another case in which the lens broke out of the tube before entering the eye. The tube is suspect in my mind.
J CATARACT REFRACT SURG-VOL 22, APRIL 1996
RANDALL]. OLSON,
MD
Salt Lake City, Utah