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Reply: Axial length and age at cataract surgery
LETTERS
3. Congdon NG, Youlin Q, Quigley H, et al. Biometry and primary angleclosure glaucoma among Chinese, white and black populations. Ophthalmology 1997; 104:1489–1495 4. Wong TY, Foster PJ, Ng TP, et al. Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:73–80 5. Wong TY, Foster PJ, Johnson GJ, et al. The relationship between ocular dimensions and refraction with adult stature: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:1237–1242 6. Goel S, Chua C, Butcher M, et al. Laser vs ultrasound biometryda study of intra- and interobserver variability. Eye 2004; 18:514–518
Reply: We thank Liu and coauthors for their interest in our paper. Unfortunately, their comments seem to have missed the point. We did not say that AL is associated with earlier age of cataract development, but rather that it is weakly associated with earlier age of cataract surgery. Clearly, cataract surgery cannot be taken as a proxy measurement for the development of cataract. We stressed that the association was weak and discussed the limitations of our study; ie, that it was retrospective so there was limited data collection. However, to our knowledge, there is no evidence that sex or adult height are risk factors for age at cataract surgery; thus, we see no reason to consider these as potential confounders. Liu and coauthors are correct in stating that our biometry method differs from the one adopted by Wong et al.1,2 However, we are not aware of any evidence to recommend their method of measuring AL 16 times or for setting applanation pressure to the intraocular pressure, particularly given its impracticality in clinical use. Their technique is at variance with the method recommended for the Humphrey 820A. The manual for this instrument suggests 10 mm Hg be used as a default. However, the instrument is usually supplied with a nonadjustable noncalibrated spring-loaded assembly to hold the probe. Could corneal indentation result in a 1.7 mm error in AL measurement per decade of increased age? We do not think so. Corneal indentation of this amount would be incredible. Finally, Wong et al. excluded from analysis patients who had a history of cataract surgery and patients who failed to achieve criteria for repeatability of biometry.1,2 If the development of cataract were associated with increased AL or if cataract caused inaccuracy in biometry from poor fixation, these exclusions would be a source of systematic bias.dStephen Tuft, MD, FRCOphth, Catey Bunce, DSc
patients after phacoemulsification,1 Wadood and coauthors comment that it would have been interesting to evaluate the efficacy of Surodex in the management of postoperative inflammation after surgery for pediatric cataracts. I would like to draw the authors’ attention to our recent article recommending the use of Surodex, particularly in the postoperative management of pediatric cataract surgery.2 We performed a retrospective review of 18 eyes of 13 children who had pediatric cataract surgery. Fourteen eyes had had posterior capsulotomy and 13 eyes had anterior vitrectomy in addition to lens aspiration. Eleven eyes received primary posterior chamber intraocular lens implantation. Our analysis showed that 2 eyes only (11.1%) developed inflammation that required additional steroid therapy. One of these children had severe atopic dermatitis, which can predisopose the eye to more postoperative inflammation. Hence, systemic steroids were used preoperatively. Four eyes received the Surodex pellet without additional topical therapy; none of these eyes developed uveitis. Only 1 eye developed elevated intraocular pressure 3 months postsurgery, but this was managed with topical betaxolol. The use of topical steroids after cataract surgery is a widely accepted practice in adults as well as in children. However, there are inherent problems of compliance and dosing, particularly in children. Surodex is useful in children because of the advantages it provides: It eliminates the problems of instilling eyedrops and removes the issue of compliance. The sustained release system allows direct application of the drug to the target site, reducing the overall steroid dose and minimizing the risk for systemic absorption. The authors were also concerned about the migration of the Surodex pellets from the anterior chamber to the posterior chamber, with potential deposition in the visual axis, which could impair visual outcome. Tan et al.3 compared the placement of the pellets between the inferior angle of the anterior chamber and in the ciliary sulcus. They found no difference in the efficacy of the antiinflammatory effect of the drug or loss of visual acuity, which was attributable to a difference in the location of placement of the pellets. We did not notice the migration of the pellets into the posterior segment in the pediatric eyes. Surodex has been found safe and effective in the control of intraocular inflammation after phacoemulsification in adults by Tan et al.3,4 as well as Wadood and coauthors.1 The suggestion by Wadood et al. together with our review suggest that Surodex is probably safe and effective as an antiinflammatory agent in selected pediatric eyes. SHU-YEN LEE, FRCSED(OPHTH) SOON-PHAIK CHEE, FRCS(G), FRCOPHTH Singapore
REFERENCES 1. Wong TY, Foster PJ, Johnson GJ, Seah SKL. Refractive errors, axial ocular dimensions, and age-related cataracts: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2003; 44:1479–1485 2. Wong TY, Foster PJ, Ng TP, et al. Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:73–80
Surodex after phacoemulsification In their discussion of the safety and efficacy of the use of the Surodex drug delivery system (Oculex Pharmaceuticals, Inc.) in
REFERENCES 1. Wadood AC, Armbrecht AM, Aspinall PA, Dhillon B. Safety and efficacy of a dexamethasone anterior segment drug delivery system in patients after phacoemulsification. J Cataract Refract Surg 2004; 30:761–768 2. Lee SY, Chee SP, Balakrishnan V, et al. Surodex in paediatric cataract surgery [letter]. Br J Ophthalmol 2003; 87:1424–1426 3. Tan DTH, Chee SP, Lim L, et al. Randomized clinical trial of Surodex steroid drug delivery system for cataract surgery; anterior versus posterior placement of two Surodex in the eye. Ophthalmology 2001; 108:2172–2181
J CATARACT REFRACTIVE SURG - VOL 31, AUGUST 2005
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3. Congdon NG, Youlin Q, Quigley H, et al. Biometry and primary angleclosure glaucoma among Chinese, white and black populations. Ophthalmology 1997; 104:1489–1495 4. Wong TY, Foster PJ, Ng TP, et al. Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:73–80 5. Wong TY, Foster PJ, Johnson GJ, et al. The relationship between ocular dimensions and refraction with adult stature: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:1237–1242 6. Goel S, Chua C, Butcher M, et al. Laser vs ultrasound biometryda study of intra- and interobserver variability. Eye 2004; 18:514–518
Reply: We thank Liu and coauthors for their interest in our paper. Unfortunately, their comments seem to have missed the point. We did not say that AL is associated with earlier age of cataract development, but rather that it is weakly associated with earlier age of cataract surgery. Clearly, cataract surgery cannot be taken as a proxy measurement for the development of cataract. We stressed that the association was weak and discussed the limitations of our study; ie, that it was retrospective so there was limited data collection. However, to our knowledge, there is no evidence that sex or adult height are risk factors for age at cataract surgery; thus, we see no reason to consider these as potential confounders. Liu and coauthors are correct in stating that our biometry method differs from the one adopted by Wong et al.1,2 However, we are not aware of any evidence to recommend their method of measuring AL 16 times or for setting applanation pressure to the intraocular pressure, particularly given its impracticality in clinical use. Their technique is at variance with the method recommended for the Humphrey 820A. The manual for this instrument suggests 10 mm Hg be used as a default. However, the instrument is usually supplied with a nonadjustable noncalibrated spring-loaded assembly to hold the probe. Could corneal indentation result in a 1.7 mm error in AL measurement per decade of increased age? We do not think so. Corneal indentation of this amount would be incredible. Finally, Wong et al. excluded from analysis patients who had a history of cataract surgery and patients who failed to achieve criteria for repeatability of biometry.1,2 If the development of cataract were associated with increased AL or if cataract caused inaccuracy in biometry from poor fixation, these exclusions would be a source of systematic bias.dStephen Tuft, MD, FRCOphth, Catey Bunce, DSc
patients after phacoemulsification,1 Wadood and coauthors comment that it would have been interesting to evaluate the efficacy of Surodex in the management of postoperative inflammation after surgery for pediatric cataracts. I would like to draw the authors’ attention to our recent article recommending the use of Surodex, particularly in the postoperative management of pediatric cataract surgery.2 We performed a retrospective review of 18 eyes of 13 children who had pediatric cataract surgery. Fourteen eyes had had posterior capsulotomy and 13 eyes had anterior vitrectomy in addition to lens aspiration. Eleven eyes received primary posterior chamber intraocular lens implantation. Our analysis showed that 2 eyes only (11.1%) developed inflammation that required additional steroid therapy. One of these children had severe atopic dermatitis, which can predisopose the eye to more postoperative inflammation. Hence, systemic steroids were used preoperatively. Four eyes received the Surodex pellet without additional topical therapy; none of these eyes developed uveitis. Only 1 eye developed elevated intraocular pressure 3 months postsurgery, but this was managed with topical betaxolol. The use of topical steroids after cataract surgery is a widely accepted practice in adults as well as in children. However, there are inherent problems of compliance and dosing, particularly in children. Surodex is useful in children because of the advantages it provides: It eliminates the problems of instilling eyedrops and removes the issue of compliance. The sustained release system allows direct application of the drug to the target site, reducing the overall steroid dose and minimizing the risk for systemic absorption. The authors were also concerned about the migration of the Surodex pellets from the anterior chamber to the posterior chamber, with potential deposition in the visual axis, which could impair visual outcome. Tan et al.3 compared the placement of the pellets between the inferior angle of the anterior chamber and in the ciliary sulcus. They found no difference in the efficacy of the antiinflammatory effect of the drug or loss of visual acuity, which was attributable to a difference in the location of placement of the pellets. We did not notice the migration of the pellets into the posterior segment in the pediatric eyes. Surodex has been found safe and effective in the control of intraocular inflammation after phacoemulsification in adults by Tan et al.3,4 as well as Wadood and coauthors.1 The suggestion by Wadood et al. together with our review suggest that Surodex is probably safe and effective as an antiinflammatory agent in selected pediatric eyes. SHU-YEN LEE, FRCSED(OPHTH) SOON-PHAIK CHEE, FRCS(G), FRCOPHTH Singapore
REFERENCES 1. Wong TY, Foster PJ, Johnson GJ, Seah SKL. Refractive errors, axial ocular dimensions, and age-related cataracts: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2003; 44:1479–1485 2. Wong TY, Foster PJ, Ng TP, et al. Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey. Invest Ophthalmol Vis Sci 2001; 42:73–80
Surodex after phacoemulsification In their discussion of the safety and efficacy of the use of the Surodex drug delivery system (Oculex Pharmaceuticals, Inc.) in
REFERENCES 1. Wadood AC, Armbrecht AM, Aspinall PA, Dhillon B. Safety and efficacy of a dexamethasone anterior segment drug delivery system in patients after phacoemulsification. J Cataract Refract Surg 2004; 30:761–768 2. Lee SY, Chee SP, Balakrishnan V, et al. Surodex in paediatric cataract surgery [letter]. Br J Ophthalmol 2003; 87:1424–1426 3. Tan DTH, Chee SP, Lim L, et al. Randomized clinical trial of Surodex steroid drug delivery system for cataract surgery; anterior versus posterior placement of two Surodex in the eye. Ophthalmology 2001; 108:2172–2181
J CATARACT REFRACTIVE SURG - VOL 31, AUGUST 2005
1479