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Accumulation of milky fluid: a late complication of cataract surgery
Accumulation of milky fluid: A late complication of cataract surgery Hisayoshi Namba, MD, Ranko Namba, MD, Takeshi Sugiura, MD, Satoshi Miyauchi, PhD ABSTRACT We describe 3 patients who presented with an accumulation of homogeneous milky fluid in the capsular bag several years after continuous curvilinear capsulorhexis, phacoemulsification, and posterior chamber intraocular lens (IOL) implantation. In each case, the entire edge of the anterior capsule opening was tightly attached to the peripheral IOL optic. The milky fluid was present in the closed chamber between the IOL optic and the posterior capsule. The fluid was sampled in 2 patients, and its concentration of sodium hyaluronate was determined by high-performance liquid chromatography. The concentration of sodium hyaluronate resembled that in normal aqueous humor. In 1 case, the protein concentration was measured and found to be elevated. Electrophoresis showed that human serum albumin was the main protein constituent. While the outcome was favorable in all 3 patients, this delayed complication of cataract surgery merits further study to clarify its etiology and pathogenesis. J Cataract Refract Surg 1999; 25:1019 –1023 © 1999 ASCRS and ESCRS
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ontinuous curvilinear capsulorhexis is an essential technique in cataract surgery. It allows phacoemulsification to be performed with greater safety and the posterior chamber intraocular lens (IOL) to be securely fixated in the capsular bag. An unusual postoperative complication, the accumulation of a milky white fluid in the space between the IOL and the posterior capsule, has been reported after cataract surgery.1,2 However, the pathogenesis, symptoms, and prognosis of this condition are unclear. We describe our experience with 3
Accepted for publication November 24, 1998 From Namba Eye Clinic, Shizuoka, Japan (Namba, Namba); Department of Ophthalmology, Medical School of Tokyo University (Sugiura), and Seikagaku Kogyou Co. Ltd. (Miyauchi), Tokyo, Japan. Presented in part at the 13th Congress of the Japanese Society of Cataract and Refractive Surgery, Sendai, Japan, May 1998. None of the authors has a proprietary interest in any product described. Reprint requests to Hisayoshi Namba, MD, Namba Eye Clinic, 4200833 5-31 Higashitakajo-machi, Shizuoka City, Shizuoka, Japan. © 1999 ASCRS and ESCRS Published by Elsevier Science Inc.
cases, including the results of biochemical analysis of the fluid.
Case Reports Case 1 A 78-year-old Japanese man with unremarkable medical history was admitted to our department in December 1991 with poor vision caused by posterior subcapsular cataracts in both eyes. Surgery was performed to remove the cataract in the left eye. The anterior chamber was maintained intraoperatively by infusion consisting of 500 mL of balanced salt solution (BSS Plus威) premixed with 0.5 mL of epinephrine diluted to 1:1000. After a fornix-based conjunctival flap was made, a 5 mm scleral tunnel incision was created. The anterior chamber was entered with a 3 mm keratome. Continuous curvilinear capsulorhexis, followed by phacoemulsification, was performed. The residual cortex was then removed with an irrigation/aspiration (I/A) tip. After the posterior capsule was polished, sodium hyaluronate (Healon威) was injected into the capsular bag. The scleral wound was enlarged to 5.0 mm, and a 3-piece poly(methyl methacrylate) (PMMA) IOL with a 5.5 mm optic was inserted in the capsular bag. The remaining Healon was aspirated from the anterior chamber 0886-3350/99/$–see front matter PII S0886-3350(99)00046-2
CASE REPORTS: NAMBA
Figure 1. (Namba) Slitlamp appearance of the anterior capsule opening in Case 1. The entire edge of the anterior capsule opening is attached to the IOL optic.
Figure 2.
with an I/A tip. Next, 0.2 mL of acetylcholine, 10 mg/mL, was injected into the anterior chamber to constrict the pupil. The scleral wound was then closed by an X-shaped 10-0 nylon suture. There were no intraoperative or postoperative complications. This same procedure of phacoemulsification and IOL implantation was performed in the patient’s right eye 1 week later. The patient’s best corrected visual acuity (BCVA) 7 days postoperatively was 20/20 in each eye. Visual acuity was unchanged over approximately 3 years. The patient moved to another prefecture in 1995; however, he returned to our hospital in September 1996, complaining of blurred vision in the left eye. His BCVA was 20/20 in the right eye and 20/30 in the left. Intraocular pressure (IOP) was 13 mm Hg in the right eye and 14 mm Hg in the left. Slitlamp examination of the left eye showed a circumfer-
ential adhesion of the margin of the anterior capsule opening to the peripheral IOL optic (Figure 1) and a mild posterior distortion of the posterior capsule. There was a pool of homogeneous milky white fluid between the posterior surface of the IOL optic and the posterior capsule (Figure 2). Small white fragments were also observed in the capsular bag. No cells or flare were detected in the anterior chamber. The intensity of the aqueous flare, measured with a laser flare meter (FM-500, Kowa Co.), was 5.3 photon count/ms. No abnormalities were observed in the cornea, vitreous body, or retina. The IOL in the right eye was well centered in the capsular bag with no noteworthy changes. The milky white fluid layer gradually became thinner; by July 1997, it had disappeared completely, although an opacity persisted in the posterior capsule (Figure 3). In July 1997, we performed a neodymium:YAG (Nd:
Figure 3. (Namba) Nine months later, the milky fluid in Case 1
Figure 4. (Namba) In Case 2, the milky fluid is present between the posterior surface of the IOL optic (open arrow) and the posterior capsule (filled arrow).
has completely disappeared. Note the opacity of the posterior capsule (filled arrow).
1020
(Namba) In Case 1, the slitlamp beam strikes the posterior surface of the IOL optic (open arrow) and the posterior capsule (filled arrow). Note the presence of the homogeneous milky white fluid between the arrows. The posterior capsule shows a slight distortion posteriorly.
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YAG) laser capsulotomy for treatment of posterior capsule opacification (PCO). One day postoperatively, the patient’s BCVA was 20/20 in the left eye.
Case 2 In November 1993, a 75-year-old Japanese woman, who had had retinal photocoagulation for branch retinal vein occlusion in the left eye 2 months earlier, had phacoemulsification and IOL implantation in the right eye. The surgical procedure was almost identical to that described in Case 1, except the scleral wound was not sutured. In February 1994, phacoemulsification and IOL implantation were performed in the patient’s left eye. There were no intraoperative or postoperative complications, and her BCVA improved to 20/20 in both eyes. She had monthly checkups for 1 year after surgery and exhibited no complications. Three years later, in November 1996, she returned complaining of blurred vision in the right eye. Her BCVA was 20/30 in the right eye and 20/10 in the left. The IOP was normal in both eyes. Slitlamp examination showed that the entire edge of the anterior capsule opening in the right eye was attached to the IOL optic, with the presence of a homogeneous-appearing pool of milky white fluid between the posterior surface of the IOL optic and the posterior capsule (Figure 4). No cells were suspended in the anterior chamber, which showed an aqueous flare intensity of 5.5 photon count/ ms. No abnormalities were observed in the cornea, vitreous body, or fundus. The IOL in the left eye was well centered in the capsular bag. There were no other remarkable changes. During a 6 month follow-up, there was no change in the milky fluid and the blurred vision persisted. With the patient’s consent, the milky fluid was aspirated under an operating microscope in May 1997. A 26 gauge needle was inserted through the temporal pars plana 3 mm from the limbus, and approximately 0.05 mL of the fluid was aspirated from just behind the center of the IOL optic in the right eye. The concentration of sodium hyaluronate in the specimen, determined by high-performance liquid chromatography (HPLC),3 was 921 ng/mL. Slitlamp biomicroscopy done the next day revealed a small tear in the posterior capsule with complete disappearance of the fluid. Best corrected visual acuity in the right eye was now 20/20.
6/30 in the right eye and 20/20 in the left. The capsular opening was occluded by the IOL optic, and fibrosis was present along the entire circumference. A homogeneous milky white fluid was observed between the posterior surface of the IOL and the posterior capsule. The aqueous flare intensity in the anterior chamber was 8.1 photon count/ms. There were no other abnormalities in the right eye and no obvious abnormalities in the left. In November 1997, the milky fluid in the right eye was sampled using the procedure described for Case 2. The concentration of sodium hyaluronate in the specimen was 24.4 g/mL. Using Lowry et al.’s method,4 the total protein concentration was 3.75 mg/mL. To examine the protein composition of the fluid in Case 3, SDS-polyacrylamide gel electrophoresis was used.5 Human serum albumin and a molecular weight marker (Daiichi Kagaku Pharmaceutical Co.) served as standards and were applied to the same gel. The protein in the fluid was diluted to 3 mg/mL with distilled water, and 3 specimens having volumes of 0.5, 2, and 10 L (corresponding to 1.5, 6, and 30 g of protein, respectively) were applied to the SDS-polyacrylamide gel. The pattern of the predominant protein band was identical to that for human serum albumin (Figure 5). A few bands suggestive of globulin fractions were also observed. Slitlamp examination the day after fluid aspiration revealed a partial rupture of the posterior capsule with complete disappearance of the fluid; BCVA in the right eye was then 20/20. The clinical findings common to the 3 patients were the following: presentation with a mild to moderate decrease in visual acuity, accumulation of milky white fluid in the closed chamber between the IOL optic and posterior capsule, and
Case 3 An 80-year-old Japanese man with no remarkable medical history had phacoemulsification and IOL implantation in the left eye in August 1994 and in the right eye 2 weeks later. The procedure described in Case 2 was followed. The IOL, a 3-piece PMMA lens with a 6.0 mm optic, was inserted in the capsular bag. There were no intraoperative or postoperative complications. In September 1994, the BCVA in both eyes was 20/20. In October 1997, the patient complained of a decrease in visual acuity in the right eye. Best corrected visual acuity was
Figure 5. (Namba) Results of SDS-polyacrylamide gel electrophoresis of the milky fluid sampled from patient 3. A: Molecular weight marker used as standard. B: Diluted specimen of fluid containing 1.5 g of protein. C: Diluted specimen of fluid containing 6 g of protein. D: Diluted specimen of fluid containing 30 g of protein. E: human serum albumin used as a standard.
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circumferential adhesion of the edge of the anterior capsule opening to the peripheral IOL optic. There were no intraoperative complications during cataract surgery, and the postoperative period was uneventful. The onset of symptoms occurred several years after cataract surgery.
Discussion The unusual condition we describe obviously differs from PCO,6 which is classified as fibrous, Elschnig pearls, and Soemmering’s ring. We excluded the presence of delayed endophthalmitis caused by a bacterial infection, e.g., Propionibacterium acnes, since the typical signs of inflammation, such as keratic precipitates or hypopyon, were absent. Recently, investigators7–9 have described the accumulation of a transparent fluid between the IOL optic and the posterior capsule, “the capsular block syndrome,” soon after surgery. In this condition, the early sealing of the anterior capsule rim to the IOL optic, with subsequent accumulation of fluid, results in a posterior distension of the posterior capsule and a forward displacement of the IOL optic. Although an accumulation of fluid in the closed chamber between the IOL optic and the posterior capsule occurs in both this syndrome and the condition we report, these disorders can be readily distinguished by their clinical characteristics. Patients with complications similar to those of our patients have been reported. Miyake and coauthors2 found a liquefied white substance between the IOL and the posterior capsule in 41 patients months to years after phacoemulsification and IOL implantation within the capsular bag; they called this condition liquefied aftercataract. They noted that in several cases, the fluid disappeared spontaneously; in other cases, it was rapidly absorbed after Nd:YAG laser capsulotomy. Eifrig1 described 3 patients in whom a milky fluid was detected between the posterior surface of an IOL and a posteriorly expanding posterior capsule in pseudophakic eyes, which he termed capsulorhexis-related lacteocrumenasia. It has been suggested7–9 that the fluid that accumulates in the capsular block syndrome involves either a residual viscoelastic substance or the retention of lens epithelial cells, their by-products, and the lens cortex. Sugiura et al. recently aspirated the fluid via the pars plana in patients with capsular block syndrome and analyzed its composition by HPLC (T. Sugiura, S. Miya1022
uchi, H. Namba, et al., “The Analysis of Liquid Substance Accumulated in the Distended Capsular Bag After Cataract Surgery,” poster presented at the XIIIth International Congress of Eye Research, Paris, France, July 1998). These investigators detected a high concentration of sodium hyaluronate in the fluid and suggested that the dilution of residual viscoelastic substances in the capsule with aqueous humor, followed by an increase in volume, could lead to a distension of the posterior capsule. We sampled the milky white fluid from 2 of our 3 patients using this method. The concentration of sodium hyaluronate in our specimens was 921.0 ng/mL (Case 2) and 24.4 g/mL (Case 3). Normally, the concentration of sodium hyaluronate in the aqueous humor of healthy humans is approximately 1 g/mL,10 while that in the vitreous body ranges from 100 to 500 g/ mL.11 The concentration of sodium hyaluronate in the specimens from our 2 cases thus resembled that in normal aqueous humor, but it was markedly below the levels of 3.0 to 9.0 mg/mL reported by Sugiura et al. Therefore, viscoelastic substances likely did not play an important role in production of the milky white fluid in our cases, although viscoelastic substances may have been retained behind the IOL after surgery. The protein concentration in the aqueous humor in normal humans is 50 to 160 g/mL,12 and that in the vitreous body is approximately 400 g/mL.13 The total protein concentration in the fluid from Case 3 in the present study, 3.75 mg/mL, markedly exceeded those values. We used SDS-polyacrylamide gel electrophoresis to separate the protein components of the fluid based on their molecular weight. In the present case, human serum albumin predominated, with small amounts of globulin fractions also present. Such electrophoretic patterns are consistent with the typical pattern reported for the aqueous humor.14 Postoperatively, residual lens epithelial cells usually undergo fibrous proliferation and produce collagen.15 Specimens of the fluid from Case 3 showed no protein components indicative of collagen. By electrophoresis, Eifrig1detected numerous proteins, including crystallin and albumin, in the milky fluid sampled from 2 patients. The intensity of aqueous flare, which reflects quantitative changes in the protein concentration in the anterior chamber,16 was normal in all 3 of our patients. This finding indicates a tight adhesion of the anterior capsule opening to the IOL optic so that the fluid and its
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protein components cannot diffuse into the anterior chamber. The mechanism for formation of this proteinaceous aqueous humor in the closed chamber between the IOL and the posterior capsule years after cataract surgery remains unclear. It is possible that the plasmoid aqueous that was trapped in the capsular bag in the early postoperative period may have undergone changes in this closed space over time. Further investigation is required to clarify the origin of the protein and the mechanism of fluid production. The prognosis of patients with this late complication of cataract surgery appears favorable. Follow-up in Case 1 revealed the development of a typical aftercataract with a spontaneous disappearance of the fluid about 9 months after his initial complaint of blurred vision. The patient’s BCVA improved after Nd:YAG laser capsulotomy was performed. In Cases 2 and 3, part of the posterior capsule was inadvertently ruptured during sampling of the fluid; by the next day, the fluid had completely disappeared and the patients’ visual acuity had improved. This rupture appeared to allow the remaining fluid to disperse into the vitreous cavity. Thus, if the volume of milky white fluid is not excessive and reduction in visual acuity is not severe, observation without specific treatment should be sufficient. However, a marked decrease in visual acuity would indicate the need for Nd:YAG laser capsulotomy.
4.
5.
6. 7.
8. 9. 10. 11.
12. 13.
14.
References
15.
1. Eifrig DE. Capsulorhexis-related lacteocrumenasia. J Cataract Refract Surg 1997; 23:450 – 454 2. Miyake K, Ota I, Miyake S, Horiguchi M. Liquefied aftercataract: a complication of continuous curvilinear capsulorhexis and intraocular lens implantation in the lens capsule. Am J Ophthalmol 1998; 125:429 – 435 3. Miyauchi S, Morita M, Kuramoto K, Horie K. Hyaluro-
16.
nan and chondroitin sulfate in rabbit tears. Curr Eye Res 1996; 15:131–135 Lowry OH, Rosebrough NJ, Farr AL, et al. Protein measurement with the Folin phenol reagent. J Biol Chem 1951; 193:265–275 Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 1970; 227:680 – 685 Apple DJ, Solomon KD, Tetz MR, et al. Posterior capsule opacification. Surv Ophthalmol 1992; 37:73–116 Davison JA. Capsular bag distension after endophacoemulsification and posterior chamber intraocular lens implantation. J Cataract Refract Surg 1990; 16:99 –108 Holtz SJ. Postoperative capsular bag distension. J Cataract Refract Surg 1992; 18:310 –317 Masket S. Postoperative complications of capsulorhexis. J Cataract Refract Surg 1993; 19:721–724 Laurent UBG. Hyaluronate in human aqueous humor. Arch Ophthalmol 1983; 101:129 –130 Balazs EA. Physicology of the vitreous body. In: Schepens CL, ed, Importance of the Vitreous Body in Retina Surgery with Special Emphasis on Reoperation. St Louis, MO, CV Mosby, 1960:29 – 48. Davson H. The intraocular fluids. In: Davson H, ed, The Eye. New York, Academic Press, 1962; vol 1, 67–145 Nordmann J. Chimie. In: Brini A, Bronner A, Gerhand JP, Nordmann J, eds, Biologie et Chirurgie du Corps Vitre´. Paris, Masson et Cie, 1968; 95–167 Mukai M. Studies on proteins of aqueous humour. [Protein fractions of normal and secondary aqueous humour]. [Japanese] Acta Soc Ophthalmol Jpn 1970; 74:1269 – 1276 Ramaekers FCS, Osborn M, Schmid E, et al. Identification of the cytoskeletal proteins in lens-forming cells, a special epitheloid cell type. Exp Cell Res 1980; 127:309 – 327 Shah SM, Spalton DJ, Taylor JC. Correlations between laser flare measurements and anterior chamber protein concentrations. Invest Ophthalmol Vis Sci 1992; 33:2878 –2884
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ontinuous curvilinear capsulorhexis is an essential technique in cataract surgery. It allows phacoemulsification to be performed with greater safety and the posterior chamber intraocular lens (IOL) to be securely fixated in the capsular bag. An unusual postoperative complication, the accumulation of a milky white fluid in the space between the IOL and the posterior capsule, has been reported after cataract surgery.1,2 However, the pathogenesis, symptoms, and prognosis of this condition are unclear. We describe our experience with 3
Accepted for publication November 24, 1998 From Namba Eye Clinic, Shizuoka, Japan (Namba, Namba); Department of Ophthalmology, Medical School of Tokyo University (Sugiura), and Seikagaku Kogyou Co. Ltd. (Miyauchi), Tokyo, Japan. Presented in part at the 13th Congress of the Japanese Society of Cataract and Refractive Surgery, Sendai, Japan, May 1998. None of the authors has a proprietary interest in any product described. Reprint requests to Hisayoshi Namba, MD, Namba Eye Clinic, 4200833 5-31 Higashitakajo-machi, Shizuoka City, Shizuoka, Japan. © 1999 ASCRS and ESCRS Published by Elsevier Science Inc.
cases, including the results of biochemical analysis of the fluid.
Case Reports Case 1 A 78-year-old Japanese man with unremarkable medical history was admitted to our department in December 1991 with poor vision caused by posterior subcapsular cataracts in both eyes. Surgery was performed to remove the cataract in the left eye. The anterior chamber was maintained intraoperatively by infusion consisting of 500 mL of balanced salt solution (BSS Plus威) premixed with 0.5 mL of epinephrine diluted to 1:1000. After a fornix-based conjunctival flap was made, a 5 mm scleral tunnel incision was created. The anterior chamber was entered with a 3 mm keratome. Continuous curvilinear capsulorhexis, followed by phacoemulsification, was performed. The residual cortex was then removed with an irrigation/aspiration (I/A) tip. After the posterior capsule was polished, sodium hyaluronate (Healon威) was injected into the capsular bag. The scleral wound was enlarged to 5.0 mm, and a 3-piece poly(methyl methacrylate) (PMMA) IOL with a 5.5 mm optic was inserted in the capsular bag. The remaining Healon was aspirated from the anterior chamber 0886-3350/99/$–see front matter PII S0886-3350(99)00046-2
CASE REPORTS: NAMBA
Figure 1. (Namba) Slitlamp appearance of the anterior capsule opening in Case 1. The entire edge of the anterior capsule opening is attached to the IOL optic.
Figure 2.
with an I/A tip. Next, 0.2 mL of acetylcholine, 10 mg/mL, was injected into the anterior chamber to constrict the pupil. The scleral wound was then closed by an X-shaped 10-0 nylon suture. There were no intraoperative or postoperative complications. This same procedure of phacoemulsification and IOL implantation was performed in the patient’s right eye 1 week later. The patient’s best corrected visual acuity (BCVA) 7 days postoperatively was 20/20 in each eye. Visual acuity was unchanged over approximately 3 years. The patient moved to another prefecture in 1995; however, he returned to our hospital in September 1996, complaining of blurred vision in the left eye. His BCVA was 20/20 in the right eye and 20/30 in the left. Intraocular pressure (IOP) was 13 mm Hg in the right eye and 14 mm Hg in the left. Slitlamp examination of the left eye showed a circumfer-
ential adhesion of the margin of the anterior capsule opening to the peripheral IOL optic (Figure 1) and a mild posterior distortion of the posterior capsule. There was a pool of homogeneous milky white fluid between the posterior surface of the IOL optic and the posterior capsule (Figure 2). Small white fragments were also observed in the capsular bag. No cells or flare were detected in the anterior chamber. The intensity of the aqueous flare, measured with a laser flare meter (FM-500, Kowa Co.), was 5.3 photon count/ms. No abnormalities were observed in the cornea, vitreous body, or retina. The IOL in the right eye was well centered in the capsular bag with no noteworthy changes. The milky white fluid layer gradually became thinner; by July 1997, it had disappeared completely, although an opacity persisted in the posterior capsule (Figure 3). In July 1997, we performed a neodymium:YAG (Nd:
Figure 3. (Namba) Nine months later, the milky fluid in Case 1
Figure 4. (Namba) In Case 2, the milky fluid is present between the posterior surface of the IOL optic (open arrow) and the posterior capsule (filled arrow).
has completely disappeared. Note the opacity of the posterior capsule (filled arrow).
1020
(Namba) In Case 1, the slitlamp beam strikes the posterior surface of the IOL optic (open arrow) and the posterior capsule (filled arrow). Note the presence of the homogeneous milky white fluid between the arrows. The posterior capsule shows a slight distortion posteriorly.
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YAG) laser capsulotomy for treatment of posterior capsule opacification (PCO). One day postoperatively, the patient’s BCVA was 20/20 in the left eye.
Case 2 In November 1993, a 75-year-old Japanese woman, who had had retinal photocoagulation for branch retinal vein occlusion in the left eye 2 months earlier, had phacoemulsification and IOL implantation in the right eye. The surgical procedure was almost identical to that described in Case 1, except the scleral wound was not sutured. In February 1994, phacoemulsification and IOL implantation were performed in the patient’s left eye. There were no intraoperative or postoperative complications, and her BCVA improved to 20/20 in both eyes. She had monthly checkups for 1 year after surgery and exhibited no complications. Three years later, in November 1996, she returned complaining of blurred vision in the right eye. Her BCVA was 20/30 in the right eye and 20/10 in the left. The IOP was normal in both eyes. Slitlamp examination showed that the entire edge of the anterior capsule opening in the right eye was attached to the IOL optic, with the presence of a homogeneous-appearing pool of milky white fluid between the posterior surface of the IOL optic and the posterior capsule (Figure 4). No cells were suspended in the anterior chamber, which showed an aqueous flare intensity of 5.5 photon count/ ms. No abnormalities were observed in the cornea, vitreous body, or fundus. The IOL in the left eye was well centered in the capsular bag. There were no other remarkable changes. During a 6 month follow-up, there was no change in the milky fluid and the blurred vision persisted. With the patient’s consent, the milky fluid was aspirated under an operating microscope in May 1997. A 26 gauge needle was inserted through the temporal pars plana 3 mm from the limbus, and approximately 0.05 mL of the fluid was aspirated from just behind the center of the IOL optic in the right eye. The concentration of sodium hyaluronate in the specimen, determined by high-performance liquid chromatography (HPLC),3 was 921 ng/mL. Slitlamp biomicroscopy done the next day revealed a small tear in the posterior capsule with complete disappearance of the fluid. Best corrected visual acuity in the right eye was now 20/20.
6/30 in the right eye and 20/20 in the left. The capsular opening was occluded by the IOL optic, and fibrosis was present along the entire circumference. A homogeneous milky white fluid was observed between the posterior surface of the IOL and the posterior capsule. The aqueous flare intensity in the anterior chamber was 8.1 photon count/ms. There were no other abnormalities in the right eye and no obvious abnormalities in the left. In November 1997, the milky fluid in the right eye was sampled using the procedure described for Case 2. The concentration of sodium hyaluronate in the specimen was 24.4 g/mL. Using Lowry et al.’s method,4 the total protein concentration was 3.75 mg/mL. To examine the protein composition of the fluid in Case 3, SDS-polyacrylamide gel electrophoresis was used.5 Human serum albumin and a molecular weight marker (Daiichi Kagaku Pharmaceutical Co.) served as standards and were applied to the same gel. The protein in the fluid was diluted to 3 mg/mL with distilled water, and 3 specimens having volumes of 0.5, 2, and 10 L (corresponding to 1.5, 6, and 30 g of protein, respectively) were applied to the SDS-polyacrylamide gel. The pattern of the predominant protein band was identical to that for human serum albumin (Figure 5). A few bands suggestive of globulin fractions were also observed. Slitlamp examination the day after fluid aspiration revealed a partial rupture of the posterior capsule with complete disappearance of the fluid; BCVA in the right eye was then 20/20. The clinical findings common to the 3 patients were the following: presentation with a mild to moderate decrease in visual acuity, accumulation of milky white fluid in the closed chamber between the IOL optic and posterior capsule, and
Case 3 An 80-year-old Japanese man with no remarkable medical history had phacoemulsification and IOL implantation in the left eye in August 1994 and in the right eye 2 weeks later. The procedure described in Case 2 was followed. The IOL, a 3-piece PMMA lens with a 6.0 mm optic, was inserted in the capsular bag. There were no intraoperative or postoperative complications. In September 1994, the BCVA in both eyes was 20/20. In October 1997, the patient complained of a decrease in visual acuity in the right eye. Best corrected visual acuity was
Figure 5. (Namba) Results of SDS-polyacrylamide gel electrophoresis of the milky fluid sampled from patient 3. A: Molecular weight marker used as standard. B: Diluted specimen of fluid containing 1.5 g of protein. C: Diluted specimen of fluid containing 6 g of protein. D: Diluted specimen of fluid containing 30 g of protein. E: human serum albumin used as a standard.
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circumferential adhesion of the edge of the anterior capsule opening to the peripheral IOL optic. There were no intraoperative complications during cataract surgery, and the postoperative period was uneventful. The onset of symptoms occurred several years after cataract surgery.
Discussion The unusual condition we describe obviously differs from PCO,6 which is classified as fibrous, Elschnig pearls, and Soemmering’s ring. We excluded the presence of delayed endophthalmitis caused by a bacterial infection, e.g., Propionibacterium acnes, since the typical signs of inflammation, such as keratic precipitates or hypopyon, were absent. Recently, investigators7–9 have described the accumulation of a transparent fluid between the IOL optic and the posterior capsule, “the capsular block syndrome,” soon after surgery. In this condition, the early sealing of the anterior capsule rim to the IOL optic, with subsequent accumulation of fluid, results in a posterior distension of the posterior capsule and a forward displacement of the IOL optic. Although an accumulation of fluid in the closed chamber between the IOL optic and the posterior capsule occurs in both this syndrome and the condition we report, these disorders can be readily distinguished by their clinical characteristics. Patients with complications similar to those of our patients have been reported. Miyake and coauthors2 found a liquefied white substance between the IOL and the posterior capsule in 41 patients months to years after phacoemulsification and IOL implantation within the capsular bag; they called this condition liquefied aftercataract. They noted that in several cases, the fluid disappeared spontaneously; in other cases, it was rapidly absorbed after Nd:YAG laser capsulotomy. Eifrig1 described 3 patients in whom a milky fluid was detected between the posterior surface of an IOL and a posteriorly expanding posterior capsule in pseudophakic eyes, which he termed capsulorhexis-related lacteocrumenasia. It has been suggested7–9 that the fluid that accumulates in the capsular block syndrome involves either a residual viscoelastic substance or the retention of lens epithelial cells, their by-products, and the lens cortex. Sugiura et al. recently aspirated the fluid via the pars plana in patients with capsular block syndrome and analyzed its composition by HPLC (T. Sugiura, S. Miya1022
uchi, H. Namba, et al., “The Analysis of Liquid Substance Accumulated in the Distended Capsular Bag After Cataract Surgery,” poster presented at the XIIIth International Congress of Eye Research, Paris, France, July 1998). These investigators detected a high concentration of sodium hyaluronate in the fluid and suggested that the dilution of residual viscoelastic substances in the capsule with aqueous humor, followed by an increase in volume, could lead to a distension of the posterior capsule. We sampled the milky white fluid from 2 of our 3 patients using this method. The concentration of sodium hyaluronate in our specimens was 921.0 ng/mL (Case 2) and 24.4 g/mL (Case 3). Normally, the concentration of sodium hyaluronate in the aqueous humor of healthy humans is approximately 1 g/mL,10 while that in the vitreous body ranges from 100 to 500 g/ mL.11 The concentration of sodium hyaluronate in the specimens from our 2 cases thus resembled that in normal aqueous humor, but it was markedly below the levels of 3.0 to 9.0 mg/mL reported by Sugiura et al. Therefore, viscoelastic substances likely did not play an important role in production of the milky white fluid in our cases, although viscoelastic substances may have been retained behind the IOL after surgery. The protein concentration in the aqueous humor in normal humans is 50 to 160 g/mL,12 and that in the vitreous body is approximately 400 g/mL.13 The total protein concentration in the fluid from Case 3 in the present study, 3.75 mg/mL, markedly exceeded those values. We used SDS-polyacrylamide gel electrophoresis to separate the protein components of the fluid based on their molecular weight. In the present case, human serum albumin predominated, with small amounts of globulin fractions also present. Such electrophoretic patterns are consistent with the typical pattern reported for the aqueous humor.14 Postoperatively, residual lens epithelial cells usually undergo fibrous proliferation and produce collagen.15 Specimens of the fluid from Case 3 showed no protein components indicative of collagen. By electrophoresis, Eifrig1detected numerous proteins, including crystallin and albumin, in the milky fluid sampled from 2 patients. The intensity of aqueous flare, which reflects quantitative changes in the protein concentration in the anterior chamber,16 was normal in all 3 of our patients. This finding indicates a tight adhesion of the anterior capsule opening to the IOL optic so that the fluid and its
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protein components cannot diffuse into the anterior chamber. The mechanism for formation of this proteinaceous aqueous humor in the closed chamber between the IOL and the posterior capsule years after cataract surgery remains unclear. It is possible that the plasmoid aqueous that was trapped in the capsular bag in the early postoperative period may have undergone changes in this closed space over time. Further investigation is required to clarify the origin of the protein and the mechanism of fluid production. The prognosis of patients with this late complication of cataract surgery appears favorable. Follow-up in Case 1 revealed the development of a typical aftercataract with a spontaneous disappearance of the fluid about 9 months after his initial complaint of blurred vision. The patient’s BCVA improved after Nd:YAG laser capsulotomy was performed. In Cases 2 and 3, part of the posterior capsule was inadvertently ruptured during sampling of the fluid; by the next day, the fluid had completely disappeared and the patients’ visual acuity had improved. This rupture appeared to allow the remaining fluid to disperse into the vitreous cavity. Thus, if the volume of milky white fluid is not excessive and reduction in visual acuity is not severe, observation without specific treatment should be sufficient. However, a marked decrease in visual acuity would indicate the need for Nd:YAG laser capsulotomy.
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