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A fluorophotometric study of the barrier function in the anterior segment of the eye after intracapsular cataract extraction
CURRENT
87
OPHTHALMOLOGY
Macular Pucker. I. Prognostic Criteria, by M.T. Trese, D.B. Chandler, Albrecht uon Graejk Arch Klin Ophthalmol 221:12-15, 1983
and R. Machemer.
Epimacular membranes are a known cause of decreased central vision. Surgical removal of these membranes often improves vision. This study shows that 33 eyes with symptomatic epimacular membranes were treated by vitreous surgery and membrane removal. Vision improved in 79%. Eyes with clinically transparent membranes, but without preoperative cystoid macular edema, were most likely to achieve good vision, while Because cystoid macular edema was the most common opaque membranes had worse visual outcomes. obstacle to improved vision, membranes should be removed before this process begins or as soon as possible thereafter. Angiography should precede consideration of surgery. Even though large parts of the internal limiting lamina of the retina were often peeled with the membranes, excellent vtston could still be obtained. It was even more surprising that eyes with transparent membranes from which most large sheets of internal limiting lamina of the retina were peeled had better prognosis for good vrision. Although breaks in the internal limiting lamina are thought to play a role in causing glial perforation along the anterior retinal surface, removal of small or large pieces of the internal limiting lamina of the retina during surgery did not appear to contribute to reformation of the membranes. None of the epimacular membranes in this series recurred during the followup period of six months to two years. (Abstract by C. Hoyt)
Comment The authors have studied preoperative clinical findings, including fluorescein angiography and postoperative visual results in 33 consecutive epimacular membranes treated by membrane stripping. Follow-up evaluations from six months to two years showed that 79% of the eyes had an improvement in visual acuity of at least two lines. They confirmed previous studies that peeling of epimacular membranes yields major and lasting improvement in vision in the majority of patients selected. Two preoperative factors are shown to have significant predictive value on the visual outcome of surgery. These are the thickness of the epimacular membrane and the presence or absence of cystoid macular edema preoperatively. Although no documentation of the length of time the membrane was present is given, the authors recommend that symptomatic macular puckers be operated on early. The paper also neglects to list the causes of the macular pucker in the patients studied. Other authors imply that epiretinal membranes formed after retinal detachment surgery are easier to peel than the idiopathic variety presumably associated with posterior vitreous detachment (Michaels RC: Am J Ophthalmol 92:628-639, 1981). Those following branch vein occlusions seem easy to peel while those following severe uveitis seem to he dillicult. The pathogenesis, be it pigment epithelial cells seeding onto the surface or glial cells growing through breaks in the internal limiting membrane, may well provide another important prognostic criterion. The paper confirms yet another major contribution to the field of vitreoretinal surgery by this group. Epimacular membrane peeling is for real. I;\s CONSTAIJI,~hKTH,
~~IF+T.KAI.I.\
A Fluorophotometric Study of the Barrier Function in the Anterior Segment of the Eye After Intracapsular Cataract Extraction, by M. Sawa, M. Araie, and T. Tanishima. Jpn J Ophthalmol 27:404-4 15, 1983 Surgical manipulations during cataract surgery give rise to a breakdown of the blood aqueous barrier which is manifested as an increase of aqueous protein, aqueous flare, and an elevation of the intraocular pressure during the postoperative period. In addition, miosis occurs during surgery, often interfering with the extraction of the lens. These responses may be suppressed by pretreatment with topical indomethacin, and this has led to the thesis that these responses to surgical manipulation are at least in part mediated by synthesis of prostaglandins that probably occurs in the iris. To assess the degree ofsurgical injury to the blood aqueous barrier and the cornea1 epithelium, quantitative evaluations of these barrier functions need to be carried out. In this study, the authors documented the
88
Surv Ophthalmol
29 (1) July-August
CURRENTOPHTHALMOLOGY
1984
permeability of the cornea1 endothelium to fluorescein following intracapsular cataract extraction. The transfer coefficient of fluorescein across the cornea1 endothelium was determined by a method of oral dye administration in 54 normal eyes. There were no significant differences in these values between young subjects and those older than 50 years. A total of 56 eyes which underwent intracapsular cataract extraction 1) those operated on using routine medications; 2) those with topical were divided into three groups: indomethacin; and 3) those with alphachymotrypsin of 7,500 X dilution. This study documents that in all three groups there was a significantly greater transfer coefftcient offluorescein across the cornea1 endothelium, showing damage of cornea1 endothelium at the time of surgery. However, the coefftcient of fluorescein was significantly less in the indomethacin group than in the other groups. Between the groups with routine medication and with chymotrypsin no significant differences were found. The authors conclude, therefore, that topical indomethacin suppressed disruption of the blood aqueous barrier, whereas chymotrypsin at the present dilution did not cause serious disruption of that barrier. (Abstract by C. Hoyt)
Comment This study involves the oral administration of fluorescein followed by monitoring of the concentration of fluorescein in the cornea and aqueous humor. This allows for an evaluation of the cornea1 endothelial permeability and, by further deduction, evaluation of the amount ofprotein in the anterior chamber, as well as the degree of inward leakage of serum components into the anterior chamber. The authors very nicely demonstrate that there is a breakdown of the cornea1 endothelial barrier to fluorescein, following uncomplicated intracapsular cataract extraction. The cornea1 endothelial permeability It is interesting to note that the cornea1 is approximately doubled six days following cataract extraction. thickness is increased only slightly in most of the groups, indicating that while the barrier function may have been partially damaged by the surgery, the pumping function, which continues to maintain the cornea in a relatively dehydrated state, remains working well. It would appear to have been an even better study had the patients been studied preoperatively, or failing this, had the other eye been studied at the same time, with each patient serving as his or her match control. This would give much more information about the endothelial permeability and the cornea1 thickness of the individual patients. Part of the calculations purport to show that since the ratio of free fluorescein to total fluorescein has been decreased from a ratio of one in some of the cases, that there is more protein in the aqueous humor binding some of the fluorescein. The authors point out that especially in the indomethacin-treated group the ratio is close to one, whereas in the other groups it is 25 or 30% less than this. There is a major flaw in this part of the study, in that four or five of the patients from the indomethacin group have a ratio greater than 1.2. On a theoretical basis this is impossible since the amount of free fluorescein can never be more than the total amount of fluorescein, since free fluorescein is a part of the total fluorescein. If these numbers are rounded off to zero, which is not an exact scientific procedure, then the ratio drops well below one. The authors have failed to explain this in their paper, and this greatly weakens this section of it. The findings as they relate to cornea1 endothelial barrier function appear to be well-substantiated throughout this paper. The findings as they relate to the increase in the aqueous protein are less well-substantiated. STL:PHL;NR. W.U.TUAN ST. LOUIS, MISSOUKI
Intraocular Foreign Body. Principles and Problems in the Management of Complicated Cases by Pars Plana Vitrectomy, by K. Heimann, H. Paulmann, and U. Tavakolian. Int Ophthalmol 6-235-242, 1983 Modern techniques of diagnosis and progress in vitreous surgery have appreciably improved the results of treatment in complicated intraocular foreign bodies. This study represents a retrospective study of the results of pars plana vitrectomy in treatment of injuries with intraocular foreign bodies. Pars plana vitrectomy was carried out in 55 1 cases of perforating injuries from June 1976 to 1981. In 41.6% of the cases, practical blinding could not be prevented. A visual acuity of 0.2 or better was present in 26.6% of the cases. The preoperative (45%) and postoperative (30%) traumatic retinal detachment have an extremely unfavorable prognosis, with a reattachment rate ofonly 40% and 21% respectively. The results in the treatment ofinjuries
87
OPHTHALMOLOGY
Macular Pucker. I. Prognostic Criteria, by M.T. Trese, D.B. Chandler, Albrecht uon Graejk Arch Klin Ophthalmol 221:12-15, 1983
and R. Machemer.
Epimacular membranes are a known cause of decreased central vision. Surgical removal of these membranes often improves vision. This study shows that 33 eyes with symptomatic epimacular membranes were treated by vitreous surgery and membrane removal. Vision improved in 79%. Eyes with clinically transparent membranes, but without preoperative cystoid macular edema, were most likely to achieve good vision, while Because cystoid macular edema was the most common opaque membranes had worse visual outcomes. obstacle to improved vision, membranes should be removed before this process begins or as soon as possible thereafter. Angiography should precede consideration of surgery. Even though large parts of the internal limiting lamina of the retina were often peeled with the membranes, excellent vtston could still be obtained. It was even more surprising that eyes with transparent membranes from which most large sheets of internal limiting lamina of the retina were peeled had better prognosis for good vrision. Although breaks in the internal limiting lamina are thought to play a role in causing glial perforation along the anterior retinal surface, removal of small or large pieces of the internal limiting lamina of the retina during surgery did not appear to contribute to reformation of the membranes. None of the epimacular membranes in this series recurred during the followup period of six months to two years. (Abstract by C. Hoyt)
Comment The authors have studied preoperative clinical findings, including fluorescein angiography and postoperative visual results in 33 consecutive epimacular membranes treated by membrane stripping. Follow-up evaluations from six months to two years showed that 79% of the eyes had an improvement in visual acuity of at least two lines. They confirmed previous studies that peeling of epimacular membranes yields major and lasting improvement in vision in the majority of patients selected. Two preoperative factors are shown to have significant predictive value on the visual outcome of surgery. These are the thickness of the epimacular membrane and the presence or absence of cystoid macular edema preoperatively. Although no documentation of the length of time the membrane was present is given, the authors recommend that symptomatic macular puckers be operated on early. The paper also neglects to list the causes of the macular pucker in the patients studied. Other authors imply that epiretinal membranes formed after retinal detachment surgery are easier to peel than the idiopathic variety presumably associated with posterior vitreous detachment (Michaels RC: Am J Ophthalmol 92:628-639, 1981). Those following branch vein occlusions seem easy to peel while those following severe uveitis seem to he dillicult. The pathogenesis, be it pigment epithelial cells seeding onto the surface or glial cells growing through breaks in the internal limiting membrane, may well provide another important prognostic criterion. The paper confirms yet another major contribution to the field of vitreoretinal surgery by this group. Epimacular membrane peeling is for real. I;\s CONSTAIJI,~hKTH,
~~IF+T.KAI.I.\
A Fluorophotometric Study of the Barrier Function in the Anterior Segment of the Eye After Intracapsular Cataract Extraction, by M. Sawa, M. Araie, and T. Tanishima. Jpn J Ophthalmol 27:404-4 15, 1983 Surgical manipulations during cataract surgery give rise to a breakdown of the blood aqueous barrier which is manifested as an increase of aqueous protein, aqueous flare, and an elevation of the intraocular pressure during the postoperative period. In addition, miosis occurs during surgery, often interfering with the extraction of the lens. These responses may be suppressed by pretreatment with topical indomethacin, and this has led to the thesis that these responses to surgical manipulation are at least in part mediated by synthesis of prostaglandins that probably occurs in the iris. To assess the degree ofsurgical injury to the blood aqueous barrier and the cornea1 epithelium, quantitative evaluations of these barrier functions need to be carried out. In this study, the authors documented the
88
Surv Ophthalmol
29 (1) July-August
CURRENTOPHTHALMOLOGY
1984
permeability of the cornea1 endothelium to fluorescein following intracapsular cataract extraction. The transfer coefficient of fluorescein across the cornea1 endothelium was determined by a method of oral dye administration in 54 normal eyes. There were no significant differences in these values between young subjects and those older than 50 years. A total of 56 eyes which underwent intracapsular cataract extraction 1) those operated on using routine medications; 2) those with topical were divided into three groups: indomethacin; and 3) those with alphachymotrypsin of 7,500 X dilution. This study documents that in all three groups there was a significantly greater transfer coefftcient offluorescein across the cornea1 endothelium, showing damage of cornea1 endothelium at the time of surgery. However, the coefftcient of fluorescein was significantly less in the indomethacin group than in the other groups. Between the groups with routine medication and with chymotrypsin no significant differences were found. The authors conclude, therefore, that topical indomethacin suppressed disruption of the blood aqueous barrier, whereas chymotrypsin at the present dilution did not cause serious disruption of that barrier. (Abstract by C. Hoyt)
Comment This study involves the oral administration of fluorescein followed by monitoring of the concentration of fluorescein in the cornea and aqueous humor. This allows for an evaluation of the cornea1 endothelial permeability and, by further deduction, evaluation of the amount ofprotein in the anterior chamber, as well as the degree of inward leakage of serum components into the anterior chamber. The authors very nicely demonstrate that there is a breakdown of the cornea1 endothelial barrier to fluorescein, following uncomplicated intracapsular cataract extraction. The cornea1 endothelial permeability It is interesting to note that the cornea1 is approximately doubled six days following cataract extraction. thickness is increased only slightly in most of the groups, indicating that while the barrier function may have been partially damaged by the surgery, the pumping function, which continues to maintain the cornea in a relatively dehydrated state, remains working well. It would appear to have been an even better study had the patients been studied preoperatively, or failing this, had the other eye been studied at the same time, with each patient serving as his or her match control. This would give much more information about the endothelial permeability and the cornea1 thickness of the individual patients. Part of the calculations purport to show that since the ratio of free fluorescein to total fluorescein has been decreased from a ratio of one in some of the cases, that there is more protein in the aqueous humor binding some of the fluorescein. The authors point out that especially in the indomethacin-treated group the ratio is close to one, whereas in the other groups it is 25 or 30% less than this. There is a major flaw in this part of the study, in that four or five of the patients from the indomethacin group have a ratio greater than 1.2. On a theoretical basis this is impossible since the amount of free fluorescein can never be more than the total amount of fluorescein, since free fluorescein is a part of the total fluorescein. If these numbers are rounded off to zero, which is not an exact scientific procedure, then the ratio drops well below one. The authors have failed to explain this in their paper, and this greatly weakens this section of it. The findings as they relate to cornea1 endothelial barrier function appear to be well-substantiated throughout this paper. The findings as they relate to the increase in the aqueous protein are less well-substantiated. STL:PHL;NR. W.U.TUAN ST. LOUIS, MISSOUKI
Intraocular Foreign Body. Principles and Problems in the Management of Complicated Cases by Pars Plana Vitrectomy, by K. Heimann, H. Paulmann, and U. Tavakolian. Int Ophthalmol 6-235-242, 1983 Modern techniques of diagnosis and progress in vitreous surgery have appreciably improved the results of treatment in complicated intraocular foreign bodies. This study represents a retrospective study of the results of pars plana vitrectomy in treatment of injuries with intraocular foreign bodies. Pars plana vitrectomy was carried out in 55 1 cases of perforating injuries from June 1976 to 1981. In 41.6% of the cases, practical blinding could not be prevented. A visual acuity of 0.2 or better was present in 26.6% of the cases. The preoperative (45%) and postoperative (30%) traumatic retinal detachment have an extremely unfavorable prognosis, with a reattachment rate ofonly 40% and 21% respectively. The results in the treatment ofinjuries