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Early publication on intraoperative retinoscopy
367
LETTERS
segment of the table is mobilized so it is flexed upward. The patient’s head is supported by a Bio-flex surgical head support (Medtronic Xomed, Inc.) stacked on a Reuben pillow (Eschmann Holdings Ltd). If this is inadequate, additional height is gained by adding a folded towel. This is usually sufficient even in the presence of severe kyphosis. An additional towel can be rolled and placed under the shoulders to provide further support and comfort. The tendency to slide downward is limited using a Velcro safety strap around the patient’s body as the patient’s posture is adjusted to adopt the Trendelenburg position necessary to render the plane of his or her face horizontal. The strapping is often unnecessary as the flexed operating table segment resists backsliding of the body during the short surgical time. There is no problem with limited leg room beneath the operating table with this positioning technique, facilitating a temporal cataract incision (Figure 1). The temporal approach is especially advantageous in Asian eyes with small palpebral fissures and sometimes overhanging brow. I also rotate the table toward me somewhat to prevent fluid from pooling (Figure 2). This is useful when dealing with kyphosis combined with scoliosis.
Figure 1. Black iris-claw IOL enclavated to midperipheral iris.
require complex intraocular maneuvers or the need to suture the IOL to the sclera. A 5.0 mm corneal or scleral incision is required. The surgery can be performed under topical anesthesia and is very quick and well tolerated. We have found the use of iris-claw IOLs for phakic or aphakic purposes to be a very effective platform for lens fixation in complex situations.
Soon-Phaik Chee, FRCOphth Singapore, Singapore
Graham Belovay, MD Iqbal Ike K. Ahmed, MD Toronto, Ontario, Canada
REFERENCE 1. Muthialu A, Rauen M, Newsom TH, Jensen L, Oetting TA. Parachute-like harness to position patients with severe kyphosis during cataract surgery. J Cataract Refract Surg 2009; 35:1332–1334
REPLY: Chee’s strategy for patient positioning seems simple and elegant using this table. With severe kyphosis, we have found that the curve of the spine is so low under the head (when the head is horizontal) that we cannot get our feet under the bed for a temporal approach. It sounds as though this bed and position allow a temporal approach, which I think would be preferred.dThomas Oetting, MS, MD
Black iris-claw intraocular lens for cosmesis In reply to the cataract surgical problem pertaining to cosmetic surgical options for a no-light-perception eye with a subluxated white cataract,1 many useful options were given. However, one option that should be considered is an opaque black iris-claw intraocular lens (IOL) (Ophtec BV) that can be enclavated to the iris (Figure 1).2 This avoids the potentially risky prospect of removing the subluxated rock-hard cataract and does not
REFERENCES 1. In: Masket S, ed, Consultation section. Cataract surgical problemJ Cataract Refract Surg, 966–972 2. Landesz M, Worst JGF, Van Rij G, Houtman WA. Opaque iris claw lens in a phakic eye to correct acquired diplopia. J Cataract Refract Surg 1997; 23:137–138
Early publication on intraoperative retinoscopy In their study concerning the use of intraoperative retinoscopy for intraocular lens (IOL) power estimation,1 Patwardhan et al. cited another report2 that used autorefractive optical biometry for IOL power calculation. They also reported the deficiencies of the latter method compared with intraoperative retinoscopy. The authors apparently overlooked my original publication3 on the subject of intraoperative retinoscopy for IOL power calculation, a technique that I have been using for approximately 30 years. Richard J. Mackool, MD Astoria, New York, USA REFERENCES 1. Patwardhan SD, Azad R, Sharma Y, Chanana B, Tyagi J. Intraoperative retinoscopy for intraocular lens power estimation in
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
368
LETTERS
cases of combined phacoemulsification and silicone oil removal. J Cataract Refract Surg 2009; 35:1190–1192 2. Ianchulev T, Salz J, Hoffer K, Albini T, Hsu H, LaBree L. Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. J Cataract Refract Surg 2005; 31:1530–1536 3. Mackool RJ. The cataract extraction-refraction-implantation technique for IOL power calculation in difficult cases. J Cataract Refract Surg 1998; 24:434–435
Early flap dislocation with perioperative brimonidine use in laser in situ keratomileusis In their article about flap dislocation,1 Mun˜oz et al. state that topical brimonidine prevents the formation of subconjunctival hemorrhages after femtosecond laser in situ keratomileusis (LASIK) but significantly increases the risk for early flap dislocation. I offer some plausible explanations for the observed flap dislocation. Immediately after LASIK, the flap is stabilized by the negative (suction) pressure of the corneal endothelial pump only; thus, dryness and adhesion of the flap to the upper tarsal conjunctiva is sufficient to cause slippage of the flap. Several hours later, however, the reepithelialization of the gutter begins to increase flap stability. Therefore, LASIK requires intact epithelium and healthy endothelium early in the postoperative period to sear the flap.2 The G-protein-coupled receptor/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. Stimulation and inhibition of the corneal cAMP/PKA pathway may play a role in important corneal functions such as wound healing and homeostasis.3 Accordingly, cAMP potentiates the stimulation of corneal epithelial migration by epidermal growth factor in vitro, suggesting that endogenous cAMP might function as a modulator of epithelial wound healing promoted by this growth factor in vivo.4 It has also been demonstrated that topical application of agents known to increase cAMP increase tear secretion.5 Given that stimulation of corneal a(2A)-adrenoceptors with brimonidine results in a dose-dependent decrease in cAMP concentration,3 topical application of this agent may interfere with
corneal epithelial wound healing or tear secretion. Finally, it has been shown that among all antiglaucoma drugs, only brimonidine decreases aqueous [Ca2C]i concentration significantly, which can lead to decreased endothelial pump function and disturbed corneal homeostasis.6 Thus, the early flap dislocation in patients exposed to perioperative topical brimonidine may result from decreased negative pressure of the corneal endothelial pump, increased flap adherence as a result of aggravation of post-LASIK dry-eye condition, delayed epithelial healing, or a combination of these. As previously mentioned, brimonidine is useful in decreasing post-LASIK hemorrhagic complications; however, predisposition to flap dislocation is a major disadvantage. Determining the exact mechanism of this complication permits safer application of brimonidine while neutralizing the pathologic pathway by appropriate medications. Comparing postoperative pachymetry measurements, results of fluorescein studies, and Schirmer tests between contralateral eyes may reveal the main mechanism. Mohammad H. Nowroozzadeh, MD Shiraz, Iran REFERENCES 1. Mun˜oz G, Albarra´n-Diego C, Sakla HF, Javaloy J. Increased risk for flap dislocation with perioperative brimonidine use in femtosecond laser in situ keratomileusis. J Cataract Refract Surg 2009; 35:1338–1342 2. American Academy of Ophthalmology. Basic and Clinical Science Course. Refractive Surgery, Section 13, 2008-2009. San Francisco, CA, American Academy of Ophthalmology, 2008 3. Grueb M, Bartz-Schmidt KU, Rohrbach JM. Adrenergic regulation of cAMP/protein kinase A pathway in corneal epithelium and endothelium. Ophthalmic Res 2008; 40:322–328 4. Nakamura M, Nishida T. Potentiation by cyclic AMP of the stimulatory effect of epidermal growth factor on corneal epithelial migration. Cornea 2003; 22:355–358 5. Gilbard JP, Rossi SR, Heyda KG, Dartt DA. Stimulation of tear secretion by topical agents that increase cyclic nucleotide levels. Invest Ophthalmol Vis Sci 1990; 31:1381–1388. Available at: http:// www.iovs.org/cgi/reprint/31/7/1381.pdf. Accessed October 24, 2009 6. Wu K-Y, Hong S-J, Wang H- Z. Effects of antiglaucoma drugs on calcium mobility in cultured corneal endothelial cells. Kaohsiung J Med Sci 2006; 22:60–67
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
LETTERS
segment of the table is mobilized so it is flexed upward. The patient’s head is supported by a Bio-flex surgical head support (Medtronic Xomed, Inc.) stacked on a Reuben pillow (Eschmann Holdings Ltd). If this is inadequate, additional height is gained by adding a folded towel. This is usually sufficient even in the presence of severe kyphosis. An additional towel can be rolled and placed under the shoulders to provide further support and comfort. The tendency to slide downward is limited using a Velcro safety strap around the patient’s body as the patient’s posture is adjusted to adopt the Trendelenburg position necessary to render the plane of his or her face horizontal. The strapping is often unnecessary as the flexed operating table segment resists backsliding of the body during the short surgical time. There is no problem with limited leg room beneath the operating table with this positioning technique, facilitating a temporal cataract incision (Figure 1). The temporal approach is especially advantageous in Asian eyes with small palpebral fissures and sometimes overhanging brow. I also rotate the table toward me somewhat to prevent fluid from pooling (Figure 2). This is useful when dealing with kyphosis combined with scoliosis.
Figure 1. Black iris-claw IOL enclavated to midperipheral iris.
require complex intraocular maneuvers or the need to suture the IOL to the sclera. A 5.0 mm corneal or scleral incision is required. The surgery can be performed under topical anesthesia and is very quick and well tolerated. We have found the use of iris-claw IOLs for phakic or aphakic purposes to be a very effective platform for lens fixation in complex situations.
Soon-Phaik Chee, FRCOphth Singapore, Singapore
Graham Belovay, MD Iqbal Ike K. Ahmed, MD Toronto, Ontario, Canada
REFERENCE 1. Muthialu A, Rauen M, Newsom TH, Jensen L, Oetting TA. Parachute-like harness to position patients with severe kyphosis during cataract surgery. J Cataract Refract Surg 2009; 35:1332–1334
REPLY: Chee’s strategy for patient positioning seems simple and elegant using this table. With severe kyphosis, we have found that the curve of the spine is so low under the head (when the head is horizontal) that we cannot get our feet under the bed for a temporal approach. It sounds as though this bed and position allow a temporal approach, which I think would be preferred.dThomas Oetting, MS, MD
Black iris-claw intraocular lens for cosmesis In reply to the cataract surgical problem pertaining to cosmetic surgical options for a no-light-perception eye with a subluxated white cataract,1 many useful options were given. However, one option that should be considered is an opaque black iris-claw intraocular lens (IOL) (Ophtec BV) that can be enclavated to the iris (Figure 1).2 This avoids the potentially risky prospect of removing the subluxated rock-hard cataract and does not
REFERENCES 1. In: Masket S, ed, Consultation section. Cataract surgical problemJ Cataract Refract Surg, 966–972 2. Landesz M, Worst JGF, Van Rij G, Houtman WA. Opaque iris claw lens in a phakic eye to correct acquired diplopia. J Cataract Refract Surg 1997; 23:137–138
Early publication on intraoperative retinoscopy In their study concerning the use of intraoperative retinoscopy for intraocular lens (IOL) power estimation,1 Patwardhan et al. cited another report2 that used autorefractive optical biometry for IOL power calculation. They also reported the deficiencies of the latter method compared with intraoperative retinoscopy. The authors apparently overlooked my original publication3 on the subject of intraoperative retinoscopy for IOL power calculation, a technique that I have been using for approximately 30 years. Richard J. Mackool, MD Astoria, New York, USA REFERENCES 1. Patwardhan SD, Azad R, Sharma Y, Chanana B, Tyagi J. Intraoperative retinoscopy for intraocular lens power estimation in
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
368
LETTERS
cases of combined phacoemulsification and silicone oil removal. J Cataract Refract Surg 2009; 35:1190–1192 2. Ianchulev T, Salz J, Hoffer K, Albini T, Hsu H, LaBree L. Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. J Cataract Refract Surg 2005; 31:1530–1536 3. Mackool RJ. The cataract extraction-refraction-implantation technique for IOL power calculation in difficult cases. J Cataract Refract Surg 1998; 24:434–435
Early flap dislocation with perioperative brimonidine use in laser in situ keratomileusis In their article about flap dislocation,1 Mun˜oz et al. state that topical brimonidine prevents the formation of subconjunctival hemorrhages after femtosecond laser in situ keratomileusis (LASIK) but significantly increases the risk for early flap dislocation. I offer some plausible explanations for the observed flap dislocation. Immediately after LASIK, the flap is stabilized by the negative (suction) pressure of the corneal endothelial pump only; thus, dryness and adhesion of the flap to the upper tarsal conjunctiva is sufficient to cause slippage of the flap. Several hours later, however, the reepithelialization of the gutter begins to increase flap stability. Therefore, LASIK requires intact epithelium and healthy endothelium early in the postoperative period to sear the flap.2 The G-protein-coupled receptor/cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. Stimulation and inhibition of the corneal cAMP/PKA pathway may play a role in important corneal functions such as wound healing and homeostasis.3 Accordingly, cAMP potentiates the stimulation of corneal epithelial migration by epidermal growth factor in vitro, suggesting that endogenous cAMP might function as a modulator of epithelial wound healing promoted by this growth factor in vivo.4 It has also been demonstrated that topical application of agents known to increase cAMP increase tear secretion.5 Given that stimulation of corneal a(2A)-adrenoceptors with brimonidine results in a dose-dependent decrease in cAMP concentration,3 topical application of this agent may interfere with
corneal epithelial wound healing or tear secretion. Finally, it has been shown that among all antiglaucoma drugs, only brimonidine decreases aqueous [Ca2C]i concentration significantly, which can lead to decreased endothelial pump function and disturbed corneal homeostasis.6 Thus, the early flap dislocation in patients exposed to perioperative topical brimonidine may result from decreased negative pressure of the corneal endothelial pump, increased flap adherence as a result of aggravation of post-LASIK dry-eye condition, delayed epithelial healing, or a combination of these. As previously mentioned, brimonidine is useful in decreasing post-LASIK hemorrhagic complications; however, predisposition to flap dislocation is a major disadvantage. Determining the exact mechanism of this complication permits safer application of brimonidine while neutralizing the pathologic pathway by appropriate medications. Comparing postoperative pachymetry measurements, results of fluorescein studies, and Schirmer tests between contralateral eyes may reveal the main mechanism. Mohammad H. Nowroozzadeh, MD Shiraz, Iran REFERENCES 1. Mun˜oz G, Albarra´n-Diego C, Sakla HF, Javaloy J. Increased risk for flap dislocation with perioperative brimonidine use in femtosecond laser in situ keratomileusis. J Cataract Refract Surg 2009; 35:1338–1342 2. American Academy of Ophthalmology. Basic and Clinical Science Course. Refractive Surgery, Section 13, 2008-2009. San Francisco, CA, American Academy of Ophthalmology, 2008 3. Grueb M, Bartz-Schmidt KU, Rohrbach JM. Adrenergic regulation of cAMP/protein kinase A pathway in corneal epithelium and endothelium. Ophthalmic Res 2008; 40:322–328 4. Nakamura M, Nishida T. Potentiation by cyclic AMP of the stimulatory effect of epidermal growth factor on corneal epithelial migration. Cornea 2003; 22:355–358 5. Gilbard JP, Rossi SR, Heyda KG, Dartt DA. Stimulation of tear secretion by topical agents that increase cyclic nucleotide levels. Invest Ophthalmol Vis Sci 1990; 31:1381–1388. Available at: http:// www.iovs.org/cgi/reprint/31/7/1381.pdf. Accessed October 24, 2009 6. Wu K-Y, Hong S-J, Wang H- Z. Effects of antiglaucoma drugs on calcium mobility in cultured corneal endothelial cells. Kaohsiung J Med Sci 2006; 22:60–67
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010