- Email: [email protected]
March consultation #4
CONSULTATION SECTION
20/16 UDVA does not properly demonstrate the loss of contrast sensitivity and quality of vision. The patient’s cornea should be supported with nonpreserved tears and low-dose corticosteroids. I would wait a minimum of 1 year after the PRK, and probably longer, before considering surgical intervention. In my experience, PRK or lamellar keratectomy will not provide the quality of the vision the patient currently experiences, and I expect significant improvement over the next 6 months to a year. A gas-permeable contact lens would likely provide resolution of the visual symptoms if the patient is willing to consider this option. As for the left eye, I would not offer surgery until the right eye achieves maximum visual rehabilitation. At this time, based on the mildly thin cornea with normal topography and low myopia, I would offer the patient thin-flap laser in situ keratomileusis (LASIK), which generally removes the issue of healing from the postoperative course. Photorefractive keratectomy is not always the safest option in corneal refractive surgery. Eric Donnenfeld, MD Rockville Centre, New York, USA
- The right eye has regular topography (Figure 2), a central superficial stromal scar (Figure 1), and good uncorrected acuity. Thus, it would be reasonable to watch and wait for further surface remodeling and resolution of symptoms. If the patient is still symptomatic at 1 year, with the ocular surface having been optimized, transepithelial phototherapeutic keratectomy (PTK) guided by the depth of the scar on OCT and the original treatment diameter should help. In general, the first step in treating a visually symptomatic superficial corneal scar is to try fitting a rigid contact lens to neutralize irregular astigmatism. However, this patient has a history of contact lens intolerance and regular topography. Therefore, it would be reasonable to jump straight to PTK. The laser used for PRK in the right eye in this case has built-in compensation for hyperopic shift in transepithelial treatment. Thus, the ablation should be refractively neutral, and in terms of the final topography, using the epithelium as a mask should have advantages over PTK with previous epithelial removal. Transepithelial treatment also confines the area of epithelium removed to the stromal ablation diameter, minimizing the area of the initial posttreatment epithelial defect. Some localized scars can be peeled using manual keratectomy. However, this scar is barely visible on OCT (Figure 3), suggesting that manual keratectomy would be less likely to work. Applying mitomycin-C (MMC) at the end of the
503
PTKdnotionally 0.02 mg/mL for 20 secondsdshould reduce the risk for haze recurrence. Measures to accelerate epithelial healing after PTK include pretreatment of underlying ocular surface disease, lubrication, and a switch to unpreserved medication. The latter is particularly important in the context of bandage soft contact lens wear postoperatively because soft lenses can absorb preservatives (eg, benzalkonium chloride) and act as a depot, potentiating toxicity and retarding healing. Contact lenses based on a phosphoryl choline copolymer may have advantages over other bandage lenses for this indication because of the large hydration shell surrounding the phosphoryl choline head group; however, this has not been proved clinically. The topographic profile (Figure 2) does not suggest that problems with a tight fit would be likely, but this should be checked. If the patient is keen to proceed with treatment in the left eye, LASIK should avoid any issues with delayed epithelial healing. Bruce Allan, MD, FRCS London, United Kingdom
- Acyclovir 400 mg 5 times a day is my usual drug and dose in this situation. Many of these cases heal promptly with anti-herpetic therapy, suggesting a herpes simplex virus (HSV) etiology. Of course, one should try to reduce medications with preservatives and eliminate antibiotics such as tobramycin and other aminoglycosides in favor of antibiotics with less epithelial toxicity. Inflammation can inhibit epithelial healing; thus, I usually continue twice daily topical corticosteroidsdnonpreserved when available. Liberal lubrication with nonpreserved artificial tears is often of benefit. If the epithelial defect persists beyond 10 days, I often prescribe 50% autologous serum drops 8 times a day. During these efforts, I typically continue the use of a high-oxygen-transmissible bandage contact lens that shows good movement with blinking at the slitlamp. I would encourage the patient to wait a minimum of 1 year from the original PRK before considering surgical intervention for the anterior stromal scar, especially in an eye like this that is near plano with otherwise good vision. In my experience, many of these types of scars diminish (disappearance of myofibroblasts and reabsorption of disordered matrix they secreted) spontaneously over time to the point that intervention dwith the attendant risk for another, more severe, nonhealing epithelial defectdis not necessary. If a decision is ultimately made that intervention is needed, I tend to favor transepithelial PTK followed
J CATARACT REFRACT SURG - VOL 40, MARCH 2014
504
CONSULTATION SECTION
by masking–smoothing to remove much of the scar and surface irregularities that were generated during the delayed healing. Remember that there is an expected 1.0 diopter (D) hyperopic shift for each 50 pulses of the excimer laser (and 0.25 to 0.40 mm of stromal tissue removal per pulse). This does not apply to the smoothing portion of the procedure because only peaks are exposed and the majority of the stroma is protected from ablation by the masking agent. In my experience, 2.0 to 3.0 D of the induced hyperopia can be safely counteracted by applying hyperopic ablation with MMC at the same treatment. Therefore, before surgery I decide, based on slitlamp examination, how much PTK is required to remove approximately 75% of the opacity and, depending on the amount of stromal PTK needed, whether I will add hyperopic PRK correction after PTK and smoothing. In many of these cases, full removal of the scar is not necessary to alleviate the patient’s symptoms and efforts to remove the entire scar often result in more troubling high hyperopia. Often, I will cover this procedure with oral acyclovir in case the original disorder was related to HSV infection. If the patient wanted to consider correction in the opposite eye, I would favor femtosecond laser–assisted LASIK as long as parameters such as corneal topography and corneal thickness were normal. However, PRK could also be considered because bilateral delayed epithelial healing after PRK is exceedingly rare. Steven E. Wilson, MD Cleveland, Ohio, USA
- Several factors can delay post-PRK reepithelialization and corneal haze, including excessive inflammation, impaired ocular surface, toxicity, and the individual tissue response. Some of these factors were significant in this case. This patient was contact lens intolerant. In many long-term contact lens users with intolerance, the conjunctiva is inflamed, blepharitis is common, and the eyes are dry, which may interfere with normal postoperative epithelial and stromal wound healing. Intraoperative traumatic and aggressive scraping of the epithelium may influence the postoperative reepithelialization rate and stromal response. Postoperatively, poor contact lens fit with excessive lens movement on the cornea or a tight fit increases inflammation and infiltrates and may affect epithelial healing and the stromal response. Topical medications such as NSAIDs and quinolones may upregulate matrix metalloproteinases (MMPs),1,2 which induce an
inflammatory response. In addition, NSAIDs may increase activity of the proinflammatory pathway and decrease corneal sensitivity.3 Massive application of preservatives (eg, preserved artificial tears) causes ocular surface toxicity and inflammation and significantly delays reepithelialization and stromal reaction. Postoperatively, the contact lens absorbs the medications, the preservatives, and the toxic material released by products of the tissue inflammation. The contact lens slowly releases toxic material and further impairs epithelial and stromal healing. Delay of epithelial healing promotes stromal haze formation. Our routine approach emphasizes preoperative evaluation of the tear function and ocular surface. It includes discontinuation of contact lens use for at least 2 to 3 weeks, preoperative treatment of blepharitis and chronic ocular surface inflammation, and application of nonpreserved artificial tears. Preoperatively, all PRK patients receive topical fluorometholone for at least 5 days and oral doxycycline 100 mg/day for 10 days. Postoperatively, doxycycline is given until reepithelialization is complete; doxycycline reduces the influence of postoperative MMPs and promotes epithelial healing. We routinely use dexamethasone phosphate 0.1% 3 times a day for 1 week to control the inflammatory response. Thereafter, fluorometholone drops are given 3 times a day during the first month. Topical gentamicin drops are applied 3 times a day for 3 days and then 2 times a day for 4 more days. Nonpreserved artificial tears are freely used. At the end of the surgery, we fit bandage contact lenses. We routinely follow the patient after 1, 3, and 7 days and 1 month. We expect the reepithelialization to be complete (or almost complete) within 3 days. If a large epithelial defect is observed after 3 days, we exchange the lens and the antibiotic drops to chloramphenicol 2 times a day. If the epithelial defect is still significant after 7 days, which is extremely rare, we discontinue the lens and patch the eye with steroid ointment and chloramphenicol drops 2 times a day. Regarding the surgical approach in the left eye, in this case with delayed epithelial healing and stromal haze formation, it is important to exclude keloid type of scarring in other parts of the body and if possible to control smoking, which may delay corneal reepithelialization. Preoperatively, it is important to reduce ocular surface inflammation in the left eye and to pretreat blepharitis if it exists. Finally, we would recommend LASIK in the left eye. However, if PRK is the only option, we would use topical MMC 0.02% for 10 seconds and closely follow the patient postoperatively. We would minimize the use of preoperative and postoperative preserved medications, avoid NSAIDs and quinolones, and use larger dose of topical steroids, preferably nonpreserved.
J CATARACT REFRACT SURG - VOL 40, MARCH 2014
20/16 UDVA does not properly demonstrate the loss of contrast sensitivity and quality of vision. The patient’s cornea should be supported with nonpreserved tears and low-dose corticosteroids. I would wait a minimum of 1 year after the PRK, and probably longer, before considering surgical intervention. In my experience, PRK or lamellar keratectomy will not provide the quality of the vision the patient currently experiences, and I expect significant improvement over the next 6 months to a year. A gas-permeable contact lens would likely provide resolution of the visual symptoms if the patient is willing to consider this option. As for the left eye, I would not offer surgery until the right eye achieves maximum visual rehabilitation. At this time, based on the mildly thin cornea with normal topography and low myopia, I would offer the patient thin-flap laser in situ keratomileusis (LASIK), which generally removes the issue of healing from the postoperative course. Photorefractive keratectomy is not always the safest option in corneal refractive surgery. Eric Donnenfeld, MD Rockville Centre, New York, USA
- The right eye has regular topography (Figure 2), a central superficial stromal scar (Figure 1), and good uncorrected acuity. Thus, it would be reasonable to watch and wait for further surface remodeling and resolution of symptoms. If the patient is still symptomatic at 1 year, with the ocular surface having been optimized, transepithelial phototherapeutic keratectomy (PTK) guided by the depth of the scar on OCT and the original treatment diameter should help. In general, the first step in treating a visually symptomatic superficial corneal scar is to try fitting a rigid contact lens to neutralize irregular astigmatism. However, this patient has a history of contact lens intolerance and regular topography. Therefore, it would be reasonable to jump straight to PTK. The laser used for PRK in the right eye in this case has built-in compensation for hyperopic shift in transepithelial treatment. Thus, the ablation should be refractively neutral, and in terms of the final topography, using the epithelium as a mask should have advantages over PTK with previous epithelial removal. Transepithelial treatment also confines the area of epithelium removed to the stromal ablation diameter, minimizing the area of the initial posttreatment epithelial defect. Some localized scars can be peeled using manual keratectomy. However, this scar is barely visible on OCT (Figure 3), suggesting that manual keratectomy would be less likely to work. Applying mitomycin-C (MMC) at the end of the
503
PTKdnotionally 0.02 mg/mL for 20 secondsdshould reduce the risk for haze recurrence. Measures to accelerate epithelial healing after PTK include pretreatment of underlying ocular surface disease, lubrication, and a switch to unpreserved medication. The latter is particularly important in the context of bandage soft contact lens wear postoperatively because soft lenses can absorb preservatives (eg, benzalkonium chloride) and act as a depot, potentiating toxicity and retarding healing. Contact lenses based on a phosphoryl choline copolymer may have advantages over other bandage lenses for this indication because of the large hydration shell surrounding the phosphoryl choline head group; however, this has not been proved clinically. The topographic profile (Figure 2) does not suggest that problems with a tight fit would be likely, but this should be checked. If the patient is keen to proceed with treatment in the left eye, LASIK should avoid any issues with delayed epithelial healing. Bruce Allan, MD, FRCS London, United Kingdom
- Acyclovir 400 mg 5 times a day is my usual drug and dose in this situation. Many of these cases heal promptly with anti-herpetic therapy, suggesting a herpes simplex virus (HSV) etiology. Of course, one should try to reduce medications with preservatives and eliminate antibiotics such as tobramycin and other aminoglycosides in favor of antibiotics with less epithelial toxicity. Inflammation can inhibit epithelial healing; thus, I usually continue twice daily topical corticosteroidsdnonpreserved when available. Liberal lubrication with nonpreserved artificial tears is often of benefit. If the epithelial defect persists beyond 10 days, I often prescribe 50% autologous serum drops 8 times a day. During these efforts, I typically continue the use of a high-oxygen-transmissible bandage contact lens that shows good movement with blinking at the slitlamp. I would encourage the patient to wait a minimum of 1 year from the original PRK before considering surgical intervention for the anterior stromal scar, especially in an eye like this that is near plano with otherwise good vision. In my experience, many of these types of scars diminish (disappearance of myofibroblasts and reabsorption of disordered matrix they secreted) spontaneously over time to the point that intervention dwith the attendant risk for another, more severe, nonhealing epithelial defectdis not necessary. If a decision is ultimately made that intervention is needed, I tend to favor transepithelial PTK followed
J CATARACT REFRACT SURG - VOL 40, MARCH 2014
504
CONSULTATION SECTION
by masking–smoothing to remove much of the scar and surface irregularities that were generated during the delayed healing. Remember that there is an expected 1.0 diopter (D) hyperopic shift for each 50 pulses of the excimer laser (and 0.25 to 0.40 mm of stromal tissue removal per pulse). This does not apply to the smoothing portion of the procedure because only peaks are exposed and the majority of the stroma is protected from ablation by the masking agent. In my experience, 2.0 to 3.0 D of the induced hyperopia can be safely counteracted by applying hyperopic ablation with MMC at the same treatment. Therefore, before surgery I decide, based on slitlamp examination, how much PTK is required to remove approximately 75% of the opacity and, depending on the amount of stromal PTK needed, whether I will add hyperopic PRK correction after PTK and smoothing. In many of these cases, full removal of the scar is not necessary to alleviate the patient’s symptoms and efforts to remove the entire scar often result in more troubling high hyperopia. Often, I will cover this procedure with oral acyclovir in case the original disorder was related to HSV infection. If the patient wanted to consider correction in the opposite eye, I would favor femtosecond laser–assisted LASIK as long as parameters such as corneal topography and corneal thickness were normal. However, PRK could also be considered because bilateral delayed epithelial healing after PRK is exceedingly rare. Steven E. Wilson, MD Cleveland, Ohio, USA
- Several factors can delay post-PRK reepithelialization and corneal haze, including excessive inflammation, impaired ocular surface, toxicity, and the individual tissue response. Some of these factors were significant in this case. This patient was contact lens intolerant. In many long-term contact lens users with intolerance, the conjunctiva is inflamed, blepharitis is common, and the eyes are dry, which may interfere with normal postoperative epithelial and stromal wound healing. Intraoperative traumatic and aggressive scraping of the epithelium may influence the postoperative reepithelialization rate and stromal response. Postoperatively, poor contact lens fit with excessive lens movement on the cornea or a tight fit increases inflammation and infiltrates and may affect epithelial healing and the stromal response. Topical medications such as NSAIDs and quinolones may upregulate matrix metalloproteinases (MMPs),1,2 which induce an
inflammatory response. In addition, NSAIDs may increase activity of the proinflammatory pathway and decrease corneal sensitivity.3 Massive application of preservatives (eg, preserved artificial tears) causes ocular surface toxicity and inflammation and significantly delays reepithelialization and stromal reaction. Postoperatively, the contact lens absorbs the medications, the preservatives, and the toxic material released by products of the tissue inflammation. The contact lens slowly releases toxic material and further impairs epithelial and stromal healing. Delay of epithelial healing promotes stromal haze formation. Our routine approach emphasizes preoperative evaluation of the tear function and ocular surface. It includes discontinuation of contact lens use for at least 2 to 3 weeks, preoperative treatment of blepharitis and chronic ocular surface inflammation, and application of nonpreserved artificial tears. Preoperatively, all PRK patients receive topical fluorometholone for at least 5 days and oral doxycycline 100 mg/day for 10 days. Postoperatively, doxycycline is given until reepithelialization is complete; doxycycline reduces the influence of postoperative MMPs and promotes epithelial healing. We routinely use dexamethasone phosphate 0.1% 3 times a day for 1 week to control the inflammatory response. Thereafter, fluorometholone drops are given 3 times a day during the first month. Topical gentamicin drops are applied 3 times a day for 3 days and then 2 times a day for 4 more days. Nonpreserved artificial tears are freely used. At the end of the surgery, we fit bandage contact lenses. We routinely follow the patient after 1, 3, and 7 days and 1 month. We expect the reepithelialization to be complete (or almost complete) within 3 days. If a large epithelial defect is observed after 3 days, we exchange the lens and the antibiotic drops to chloramphenicol 2 times a day. If the epithelial defect is still significant after 7 days, which is extremely rare, we discontinue the lens and patch the eye with steroid ointment and chloramphenicol drops 2 times a day. Regarding the surgical approach in the left eye, in this case with delayed epithelial healing and stromal haze formation, it is important to exclude keloid type of scarring in other parts of the body and if possible to control smoking, which may delay corneal reepithelialization. Preoperatively, it is important to reduce ocular surface inflammation in the left eye and to pretreat blepharitis if it exists. Finally, we would recommend LASIK in the left eye. However, if PRK is the only option, we would use topical MMC 0.02% for 10 seconds and closely follow the patient postoperatively. We would minimize the use of preoperative and postoperative preserved medications, avoid NSAIDs and quinolones, and use larger dose of topical steroids, preferably nonpreserved.
J CATARACT REFRACT SURG - VOL 40, MARCH 2014