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Nonvitrectomizing Vitreous Surgery
Letters to the Editor Diode Laser for ROP Dear Editor: We read with interest Coats et al’s article on involution of threshold retinopathy of prematurity (ROP) after diode laser photocoagulation.1 We agree that there is a need for guidelines as to when to intervene surgically for eyes that are at risk for progressive stage 4 ROP. We addressed this issue earlier this year.2 Using a generalized estimating equation model, we determined that features predictive of progressive stage 4A ROP after laser treatment for threshold ROP were vitreous state, quadrants of plus disease, and clock hours of ridge elevation, whereas quadrants of neovascularization itself were not. However, in an earlier study we found that neovascularization portended a poor surgical outcome, supporting the importance of complete laser treatment, including skip lesions at the time of threshold3 or type 1 prethreshold diagnosis. We also found that most infants did not develop retinal detachment (RD) until at least 2 weeks after laser, except for one infant who required surgery for stage 4B ROP within 1 week of laser treatment. We were interested to find that the authors also found vitreous state, plus disease, and a distinction between ridge and neovascularization to be important. Besides the authors’ recommendations to define plus disease as resolving or present, it is important to note that plus disease can seemingly recur. This, we believe, is an indicator of progressive stage 4 ROP. It will be important to study vessel tortuosity and dilation with photographic documentation in future studies. We absolutely concur with the authors that there is a need to study features predictive of progressive RD in ROP. We hope that both our studies will highlight the importance of funding a multicenter study to address features predictive of progressive stage 4 ROP so as to define a window of time for surgical intervention. MARY ELIZABETH HARTNETT, MD JANET R. MCCOLM, PHD Chapel Hill, North Carolina References 1. Coats DK, Miller AM, Brady-McCreery KM, et al. Involution of threshold retinopathy of prematurity after diode laser photocoagulation. Ophthalmology 2004;111:1894 – 8. 2. Hartnett ME, McColm JR. Retinal features predictive of progressive stage 4 retinopathy of prematurity. Retina 2004;24: 237– 41. 3. Hartnett ME. Features associated with surgical outcome in patients with stages 4 and 5 retinopathy of prematurity. Retina 2003;23:322–9.
Author reply Dear Editor: We appreciate Drs Hartnett and McColm’s interest in our article. We reemphasize a point that we made in the article and a point with which Drs Hartnett and McColm seem to
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concur. There is a need to develop better guidelines regarding when to intervene surgically for eyes that are at risk for progressive stage 4 retinopathy of prematurity. We do not feel that the present treatment paradigm for retinopathy of prematurity will stand the test of time. Eventually, we believe that nonsurgical treatments will become available to prevent or treat retinopathy of prematurity. Until then, it is our opinion that there will be a trend away from extensive ablative treatment of eyes with intermediate risk of progression in favor of ablative therapy only for those eyes at highest risk, combined with strategies designed to intervene surgically for eyes at highest risk for developing a progressive retinal detachment (RD) after ablative treatment. Such a strategy, if successful, would maximize the number of eyes salvaged, while minimizing the number of eyes treated. Identification of eyes at highest risk of developing an RD and after treatment with careful evaluation of novel strategies to target specifically this group of high-risk eyes for additional intervention, we believe, is of utmost importance. We agree with Drs Hartnett and McColm’s comments that plus disease can recur. We have seen this periodically, even in eyes where the neovascularization initially completely resolved, only to recur again later. This has usually, but not always, been seen in association with skip areas in the ablative pattern. Regarding risk factors predictive of progressive RD, a subsequent publication from our group will address this issue in the near future. DAVID K. COATS, MD AARON M. MILLER, MD KATHRYN M. BRADY-MCCREERY, MD ERIC R. HOLZ, MD EVELYN A. PAYSSE, MD Houston, Texas
Nonvitrectomizing Vitreous Surgery Dear Editor: Pars plana vitrectomy with removal of epiretinal membranes (ERMs) improves vision and metamorphosis in patients with epimacular proliferation.1,2 However, the postoperative visual improvement is often reduced by the development and progression of nuclear sclerotic cataract, the most common postoperative complication of vitrectomy for epimacular proliferation.1– 4 Although the cause of postoperative nuclear sclerotic cataract is still unclear, an effective method to prevent it may be nonvitrectomizing vitreous surgery (NVVS)—that is, vitrectomy without any fluid irrigation.5,6 However, there are technical disadvantages of NVVS—for example, intraoperative and/or immediate postoperative hypotony that leads to a poor view of the fundus due to the deformation of the globe.5,6 The hypotony is caused by vitreous prolapse from the 20-gauge sclerotomy sites during the procedures. To remedy this problem, we
Letters to the Editor employed a 25-gauge vitrectomy system (Bausch & Lomb, Rochester, NY; DORC International, Zuidland, The Netherlands)7,8 for NVVS. We have thus far used this technique in 12 eyes of 12 patients (8 women and 4 men), whose ages ranged from 42 to 70 years (mean, 61.8). The surgical techniques described by Saito et al5 were modified as follows. The first 25-gauge trocar was inserted transconjunctivally 3.5 mm from the limbus in the superotemporal quadrant. Immediately after the trocar holder was removed, a plug was inserted into the trocar to prevent vitreous prolapse. A second trocar was then inserted into the superonasal quadrant. A 25-gauge fiberoptic light pipe and 25-gauge microhooked needle were introduced through the 2 trocars without any prior cutting of the vitreous. After the edge of the ERM was caught and freed by the 25-gauge microhook, the membranes were peeled and removed from the eye with a 25-gauge microforceps. If remnants of the peeled ERMs floating in the vitreous were extensive, they were cut and aspirated by a 25-gauge cutter, with caution taken not to aspirate extra vitreous. Finally, the trocars were carefully removed, and the sclerotomies were not sutured. In one eye, NVVS was performed using only one port. In this case, the fundus was viewed not by endoillumination but by a slit-lamp illumination system installed in a surgical microscope (Visulux, Carl Zeiss, Oberkochen, Germany). The rest of the procedure was the same as with the 2-port system. In all eyes, the visibility of the fundus was good throughout the surgical procedures, and the ERMs were peeled and removed without any complications except for minor retinal hemorrhages. The preoperative and immediate postoperative intraocular pressures (IOPs) were measured with the TonoPen XL (Mentor, Norwell, MA) in 7 eyes and ranged from 12 to 20 mmHg (17.6⫾2.8 [mean ⫾ standard deviation]) and 5 to 12 mmHg (7.9⫾2.7), respectively. One day after the surgery, the IOPs returned to preoperative levels in all eyes. In 11 of 12 eyes, liquid was not infused throughout the procedure. The other eye had ERMs that were recognized as being extensive only after they were peeled off. Thus, the use of a 25-gauge cutter with fluid infusion was necessary. In this case, the 2-port system was converted to a 3-port system by starting infusion through 1 of the 2 preplaced trocars. The third trocar was then inserted after elevating IOP, and the infusion tube was switched to the third trocar. The surgical time ranged from 6 to 30 minutes (mean, 15.8). At 6 months postoperatively, the best-corrected visual acuity improved by ⱖ2 lines in 11 eyes and was unchanged in 1 eye. No signs of development or progression of nuclear sclerotic cataract or recurrent ERMs were observed during the follow-up period of 6 to 18 months (mean, 10.9). Our findings show that the use of the 25-gauge system is more beneficial than the conventional 20-gauge system for preventing intraoperative and/or immediate postoperative hypotony caused by vitreous prolapse during surgery. The main reason for this is that the 25-gauge system requires a smaller sclerotomy opening, which is approximately one fourth to one third the area of the 20-gauge sclerotomy opening. In addition, the use of a trocar system enables surgeons to exert less pressure on the eye while inserting
instruments into it. If severe hypotony or uncontrollable intraocular hemorrhage occurs, however, liquid infusion should be started promptly. Even in such cases, the 25-gauge system is better than the 20-gauge system because irrigation can be started by just inserting an infusion port into 1 of the 2 preplaced trocars. Also, no need for suturing the sclerotomy sites and conjunctiva makes the surgery shorter and less invasive. In one case, we performed 1-port NVVS using a surgical microscope with slit-lamp illumination. The procedure was simpler than with the 2-port technique; however, the visibility of the fundus with the slit-lamp illumination was not as good as with a light pipe. This technique is one option in NVVS; however, we did not find any greater benefit. Although more studies with a larger number of patients are necessary to confirm the efficacy and safety of our technique, we recommend the use of the 25-gauge system as a useful modification of NVVS. SHUNJI KUSAKA, MD HIROSHI SHIMOJYO, MD TAKASHI OSHITA, MD KIYOMI FUJII, MD Osaka, Japan References 1. Margherio RR, Cox MS Jr, Trese MT, et al. Removal of epimacular membranes. Ophthalmology 1985;92:1075– 83. 2. de Bustros S, Thompson JT, Michels RG, et al. Vitrectomy for idiopathic epiretinal membranes causing macular pucker. Br J Ophthalmol 1988;72:692–5. 3. Cherfan GM, Michels RG, de Bustros S, et al. Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker. Am J Ophthalmol 1991;111:434 – 8. 4. Melberg NS, Thomas MA. Nuclear sclerotic cataract after vitrectomy in patient younger than 50 years of age. Ophthalmology 1995;102:1466 –71. 5. Saito Y, Lewis JM, Park I, et al. Nonvitrectomizing vitreous surgery: a strategy to prevent postoperative nuclear sclerosis. Ophthalmology 1999;106:1541–5. 6. Sawa M, Saito Y, Hayashi A, et al. Assessment of nuclear sclerosis after nonvitrectomizing vitreous surgery. Am J Ophthalmol 2001;132:356 – 62. 7. Fujii GY, De Juan E Jr, Humayun MS, et al. A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 2002;109:1807–12. 8. Fujii GY, De Juan E Jr, Humayun MS, et al. Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery. Ophthalmology 2002;109:1814 –20.
Corneal Thickness after Refractive Surgery Dear Editor: Generally, treating to a target intraocular pressure (IOP) that the physician believes will prevent long-term progression is essential in the treatment of primary open-angle glaucoma (POAG). Consequently, an accurate measurement of the pressure (e.g., Goldmann applanation tonometry) is vital to assess the efficacy of treatment, which then can be confirmed by long-term follow-up of the visual field and optic disc.
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Author reply Dear Editor: We appreciate Drs Hartnett and McColm’s interest in our article. We reemphasize a point that we made in the article and a point with which Drs Hartnett and McColm seem to
1636
concur. There is a need to develop better guidelines regarding when to intervene surgically for eyes that are at risk for progressive stage 4 retinopathy of prematurity. We do not feel that the present treatment paradigm for retinopathy of prematurity will stand the test of time. Eventually, we believe that nonsurgical treatments will become available to prevent or treat retinopathy of prematurity. Until then, it is our opinion that there will be a trend away from extensive ablative treatment of eyes with intermediate risk of progression in favor of ablative therapy only for those eyes at highest risk, combined with strategies designed to intervene surgically for eyes at highest risk for developing a progressive retinal detachment (RD) after ablative treatment. Such a strategy, if successful, would maximize the number of eyes salvaged, while minimizing the number of eyes treated. Identification of eyes at highest risk of developing an RD and after treatment with careful evaluation of novel strategies to target specifically this group of high-risk eyes for additional intervention, we believe, is of utmost importance. We agree with Drs Hartnett and McColm’s comments that plus disease can recur. We have seen this periodically, even in eyes where the neovascularization initially completely resolved, only to recur again later. This has usually, but not always, been seen in association with skip areas in the ablative pattern. Regarding risk factors predictive of progressive RD, a subsequent publication from our group will address this issue in the near future. DAVID K. COATS, MD AARON M. MILLER, MD KATHRYN M. BRADY-MCCREERY, MD ERIC R. HOLZ, MD EVELYN A. PAYSSE, MD Houston, Texas
Nonvitrectomizing Vitreous Surgery Dear Editor: Pars plana vitrectomy with removal of epiretinal membranes (ERMs) improves vision and metamorphosis in patients with epimacular proliferation.1,2 However, the postoperative visual improvement is often reduced by the development and progression of nuclear sclerotic cataract, the most common postoperative complication of vitrectomy for epimacular proliferation.1– 4 Although the cause of postoperative nuclear sclerotic cataract is still unclear, an effective method to prevent it may be nonvitrectomizing vitreous surgery (NVVS)—that is, vitrectomy without any fluid irrigation.5,6 However, there are technical disadvantages of NVVS—for example, intraoperative and/or immediate postoperative hypotony that leads to a poor view of the fundus due to the deformation of the globe.5,6 The hypotony is caused by vitreous prolapse from the 20-gauge sclerotomy sites during the procedures. To remedy this problem, we
Letters to the Editor employed a 25-gauge vitrectomy system (Bausch & Lomb, Rochester, NY; DORC International, Zuidland, The Netherlands)7,8 for NVVS. We have thus far used this technique in 12 eyes of 12 patients (8 women and 4 men), whose ages ranged from 42 to 70 years (mean, 61.8). The surgical techniques described by Saito et al5 were modified as follows. The first 25-gauge trocar was inserted transconjunctivally 3.5 mm from the limbus in the superotemporal quadrant. Immediately after the trocar holder was removed, a plug was inserted into the trocar to prevent vitreous prolapse. A second trocar was then inserted into the superonasal quadrant. A 25-gauge fiberoptic light pipe and 25-gauge microhooked needle were introduced through the 2 trocars without any prior cutting of the vitreous. After the edge of the ERM was caught and freed by the 25-gauge microhook, the membranes were peeled and removed from the eye with a 25-gauge microforceps. If remnants of the peeled ERMs floating in the vitreous were extensive, they were cut and aspirated by a 25-gauge cutter, with caution taken not to aspirate extra vitreous. Finally, the trocars were carefully removed, and the sclerotomies were not sutured. In one eye, NVVS was performed using only one port. In this case, the fundus was viewed not by endoillumination but by a slit-lamp illumination system installed in a surgical microscope (Visulux, Carl Zeiss, Oberkochen, Germany). The rest of the procedure was the same as with the 2-port system. In all eyes, the visibility of the fundus was good throughout the surgical procedures, and the ERMs were peeled and removed without any complications except for minor retinal hemorrhages. The preoperative and immediate postoperative intraocular pressures (IOPs) were measured with the TonoPen XL (Mentor, Norwell, MA) in 7 eyes and ranged from 12 to 20 mmHg (17.6⫾2.8 [mean ⫾ standard deviation]) and 5 to 12 mmHg (7.9⫾2.7), respectively. One day after the surgery, the IOPs returned to preoperative levels in all eyes. In 11 of 12 eyes, liquid was not infused throughout the procedure. The other eye had ERMs that were recognized as being extensive only after they were peeled off. Thus, the use of a 25-gauge cutter with fluid infusion was necessary. In this case, the 2-port system was converted to a 3-port system by starting infusion through 1 of the 2 preplaced trocars. The third trocar was then inserted after elevating IOP, and the infusion tube was switched to the third trocar. The surgical time ranged from 6 to 30 minutes (mean, 15.8). At 6 months postoperatively, the best-corrected visual acuity improved by ⱖ2 lines in 11 eyes and was unchanged in 1 eye. No signs of development or progression of nuclear sclerotic cataract or recurrent ERMs were observed during the follow-up period of 6 to 18 months (mean, 10.9). Our findings show that the use of the 25-gauge system is more beneficial than the conventional 20-gauge system for preventing intraoperative and/or immediate postoperative hypotony caused by vitreous prolapse during surgery. The main reason for this is that the 25-gauge system requires a smaller sclerotomy opening, which is approximately one fourth to one third the area of the 20-gauge sclerotomy opening. In addition, the use of a trocar system enables surgeons to exert less pressure on the eye while inserting
instruments into it. If severe hypotony or uncontrollable intraocular hemorrhage occurs, however, liquid infusion should be started promptly. Even in such cases, the 25-gauge system is better than the 20-gauge system because irrigation can be started by just inserting an infusion port into 1 of the 2 preplaced trocars. Also, no need for suturing the sclerotomy sites and conjunctiva makes the surgery shorter and less invasive. In one case, we performed 1-port NVVS using a surgical microscope with slit-lamp illumination. The procedure was simpler than with the 2-port technique; however, the visibility of the fundus with the slit-lamp illumination was not as good as with a light pipe. This technique is one option in NVVS; however, we did not find any greater benefit. Although more studies with a larger number of patients are necessary to confirm the efficacy and safety of our technique, we recommend the use of the 25-gauge system as a useful modification of NVVS. SHUNJI KUSAKA, MD HIROSHI SHIMOJYO, MD TAKASHI OSHITA, MD KIYOMI FUJII, MD Osaka, Japan References 1. Margherio RR, Cox MS Jr, Trese MT, et al. Removal of epimacular membranes. Ophthalmology 1985;92:1075– 83. 2. de Bustros S, Thompson JT, Michels RG, et al. Vitrectomy for idiopathic epiretinal membranes causing macular pucker. Br J Ophthalmol 1988;72:692–5. 3. Cherfan GM, Michels RG, de Bustros S, et al. Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker. Am J Ophthalmol 1991;111:434 – 8. 4. Melberg NS, Thomas MA. Nuclear sclerotic cataract after vitrectomy in patient younger than 50 years of age. Ophthalmology 1995;102:1466 –71. 5. Saito Y, Lewis JM, Park I, et al. Nonvitrectomizing vitreous surgery: a strategy to prevent postoperative nuclear sclerosis. Ophthalmology 1999;106:1541–5. 6. Sawa M, Saito Y, Hayashi A, et al. Assessment of nuclear sclerosis after nonvitrectomizing vitreous surgery. Am J Ophthalmol 2001;132:356 – 62. 7. Fujii GY, De Juan E Jr, Humayun MS, et al. A new 25-gauge instrument system for transconjunctival sutureless vitrectomy surgery. Ophthalmology 2002;109:1807–12. 8. Fujii GY, De Juan E Jr, Humayun MS, et al. Initial experience using the transconjunctival sutureless vitrectomy system for vitreoretinal surgery. Ophthalmology 2002;109:1814 –20.
Corneal Thickness after Refractive Surgery Dear Editor: Generally, treating to a target intraocular pressure (IOP) that the physician believes will prevent long-term progression is essential in the treatment of primary open-angle glaucoma (POAG). Consequently, an accurate measurement of the pressure (e.g., Goldmann applanation tonometry) is vital to assess the efficacy of treatment, which then can be confirmed by long-term follow-up of the visual field and optic disc.
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