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Sudden Bilateral Visual Loss in a Diabetic Man
Sudden Bilateral Visual Loss in a Diabetic Man AARON R. FLORKOWSKI, MD; RICHARD GOLDEN, MD; YADAVINDER SOOCH, MS; ROHIT KRISHNA, MD
ABSTRACT: This is a report of a case of the development of acute bilateral cataracts in a diabetic patient. A 28year-old man presented to the emergency room with a 4-day history of acutely diminished vision. The patient had a recent history of hyperglycemia. On examination, vision was noted to be count-fingers bilaterally; both lenses were intumescent with dense cortical opacities.
After 4 weeks, the cataracts had not resolved and cataract extraction surgery was performed, with improvement of the patient’s vision. A review of the mechanism of this infrequent presentation of cataract is presented. KEY INDEXING TERMS: Diabetes; Cataract; Hyperglycemia; Hexokinase; Aldehyde reductase. [Am J Med Sci 2005;329(2):99–101.]
O
After examination and discussion, the patient was diagnosed with bilateral acute diabetic cataracts, a rare presentation of diabetic cataract that develops dramatically in less than 1 day.
cular manifestations of diabetes mellitus include disorders of the retina, lens, cornea, and extraocular muscles. A case of acute diabetic cataract is presented with successful surgical management. Case Report
A 28-year-old man presented to the emergency room with a 4-day history of acute loss of vision bilaterally. The patient stated that he enjoyed good vision until waking with severely decreased vision in both eyes accompanied by photophobia, dryness, and redness. He had no significant ocular history and denied any recent trauma or visual symptoms prior to the sudden loss of vision. He denied any recent illnesses. His past medical history was significant for diabetes mellitus type 2 diagnosed 1 year earlier and bipolar disorder. Fasting blood sugar reportedly averaged 200 mg/dL but was 474 mg/dL upon presentation in the emergency department. His medications included Glucophage, insulin, venlafaxine (Effexor), simvastatin (Zocor), lamotrigine (Lomictal), quetiapine fumarate (Seroquel), zolpidem tartrate (Ambien), and clonazepam (Klonopin). At initial examination (Figure 1), the patient’s visual acuity was counting fingers at 4 inches OU. Pupil examination findings were normal, as was intraocular pressure. Slit-lamp examination was notable for mild conjunctival injection and shallow anterior chambers. Lenses were extremely intumescent with dense cortical opacities and prominent water clefts (Figure 2). There was no view of the retina. B-scan ultrasonogram was unremarkable. The patient was followed for 4 weeks, with no change in examination findings. Cataract extraction was then performed in the left eye. The lens was removed with phacoemulsification and a posterior chamber intraocular lens was implanted. The patient was seen on postoperative day 1; vision was improved to 20/40 OS (left eye). Examination of the retina revealed an apparently healthy retina with no sign of retinopathy. The patient did not keep subsequent appointments and was lost to follow-up.
From the University of Missouri-Kansas City (ARF, RG, YS) and the Eye Foundation of Kansas City (RK), Kansas City, Missouri. Submitted March 17, 2004; accepted July 28, 2004. Correspondence: Rohit Krishna, MD, University of MissouriKansas City, Department of Ophthalmology, Eye Foundation of Kansas City, 2300 Holmes Street, Kansas City, MO 64108 (Email: [email protected]). THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES
Discussion Diabetes mellitus, a disorder of carbohydrate metabolism in which sugars are not properly oxidized because of lack of insulin or insulin resistance, may lead to numerous systemic and ocular complications. Ocular manifestations of the disease include retinopathy, extraocular muscle paresis, corneal compromise, and cataracts.1 The association between cataract formation and diabetes mellitus is well described in the literature,2 and the incidence of cataract formation is usually higher in patients with a longer duration of disease. Although acceleration of typical senile cataracts is commonly seen in patients with diabetes, true acute diabetic cataracts usually occur in patients younger than 40 years of age. They are rare, with a prevalence of less than 1% in diabetic patients. They are commonly referred to as “juvenile” diabetic cataracts.3 Cataracts brought about by acute hyperglycemia may arise quickly, as seen in our patient, even within hours or days. Within that time, these lenses can progress from clear to completely opaque.4 Treatment of acute hyperglycemia has been associated with arrest, partial reversal, and even further progression of the cataract. If no permanent lenticular cell damage occurs, the cataractous changes may rarely regress; however, complete reversal is rare.5 Acute diabetic cataracts are typically bilateral and morphologically include anterior or posterior subcapsular “snowflake opacities,” fine stellate needle-shaped cortical opacities, and subcapsular vacuoles and clefts.6 Although numerous mechanisms have been proposed for the development of acute diabetic cata99
Sudden Bilateral Visual Loss in a Diabetic Man
Figure 1. A 28-year-old man with acute, bilateral dense cortical cataracts.
racts, overloading of the hexokinase pathway and subsequent routing of substrate into the alternate aldose reductase pathway is the favored theory. The hexokinase pathway is the main route of glucose metabolism within the lens. However, with poorly managed glycemic control, this enzyme becomes saturated and aldose reductase, an enzyme with lesser affinity for glucose than hexokinase, is able to convert the extra glucose into the sugar alcohol sorbitol and eventually fructose. Neither sorbitol nor fructose is able to penetrate cell membranes, so once formed they accumulate to high levels intracellularly within the lens, creating a hyperosmolar state. The resulting osmotic influx of fluid causes swelling of the lens fibers; at this point, these changes are potentially reversible.7 These mechanisms can initially lead to refractive changes. A myopic shift is observed as intracellular sugar concentrations rise. As blood sugar levels decrease in response to therapy, reverse flow is thought to take place, causing a transitory hyperopic shift.8 Long-term maintenance of lens clarity is dependent on low intracellular water concentration. Transport pumps within the cell membrane of the lens actively exchange ions between the lens cells and aqueous humor. Water passively moves across the cell membranes following Na⫹, maintaining a relative state of dehydration. The intracellular
swelling initiated by the retention of sorbitol and fructose increases permeability to cations and eventually overruns the Na⫹-K⫹ pump’s ability to maintain normal ratios across the cell membrane. This further worsens the hyperosmolar state, resulting in protein denaturation and increased opacification, which becomes irreversible as the swollen lens fibers rupture.7,9 Interestingly, numerous reports of cataract formation after treatment of hyperglycemia have been reported in the literature. These reports of cataract formation in the hypo- and euglycemic patient seem to contradict the concept of hyperosmolar swelling as the sole cause of diabetic cataract formation and have led to the postulation that the destabilization of hexokinase by glucose deprivation may be a key element of hypoglycemic cataract formation. Thus, maintenance of normal blood sugar and prevention of repeated fluctuations in either direction probably reduces the risk of cataract formation.10 Glycosylation, a known risk factor for the development of diabetic retinopathy, has also been studied in the incidence of cataract formation. At one time it was hypothesized that glycosylation of lens proteins increased their susceptibility to light scattering effects and brunescence.9 However, studies since have shown no such correlation.11 Additionally, the HbA1C, a measure of bloodstream glycosylation, does not appear to correlate with the development of diabetic cataracts and thus cannot be relied upon in predicting patients at risk for their development.12 Conclusion Although senile cataracts commonly occur at an earlier age and progress more rapidly in diabetic patients, irreversible development of diabetic cataract acutely, as seen in our patient, is a rarely reported entity. It is probable that the development of acute cataracts in our patient was exacerbated by elevated glucose levels beyond the normal range. The mechanism of his cataract formation most likely adheres to the physiologic and biochemical principles reviewed, dealing with the aldose reductase pathway and osmotic influx of water into a hyperosmotic lens. The irreversibility of his cataract, which required surgical intervention, is a reflection of the severity of this disease. Surgical removal of the cataractous lens can result in successful visual outcomes. References
Figure 2. Slit-lamp photograph of same patient, right eye. The lens is entirely opacified.
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1. Dorland WA, editor. Dorland’s illustrated medical dictionary. Philadelphia (PA): Saunders; 1981.
February 2005 Volume 329 Number 2
Florkowski et al.
2. Bradbury MJ, Aiello LM. In: Kozak G, editor. Diabetic eye disease in clinical diabetes mellitus, 1st ed. Philadelphia (PA): WB Saunders; 1982. p. 256 –7. 3. Vinding T, Nielsen NV. Two cases of acutely developed cataract in diabetes mellitus. Acta Ophthalmol 1984;62:373–7. 4. Roberts W. Rapid lens changes in diabetes mellitus. Am J Ophthalmol 1950;33:1283–5. 5. Gelvin JB, Thonn VA. The formation and reversal of acute cataracts in diabetes mellitus. J Am Optom Assoc 1993;64: 471– 4. 6. Caird FI, Prie A, Ramsell TG. Diabetes and the eye. Oxford (UK): Blackwell Scientific Publications; 1969. p. 127–34. 7. Kinoshita JH. Mechanisms initiating cataract formation. Invest Ophthalmol Vis Sci 1974;13:713–25.
THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES
8. Duke-Elder WS. The neurology of vision motor and optical anomalies. In: Duke-Elder WS, editor. Textbook of ophthalmology, vol. 4. St. Louis (MO): CV Mosby; 1949. p. 4364 – 6. 9. Kador PF, Kinoshita JH. Diabetic and galactosaemic cataracts. In: Human cataract formation. Ciba Foundation Symposium 106. London (UK): Pitman; 1984. p. 110 –31. 10. Chylach LT, Cheng HM. Sugar metabolism in the crystaline lens. Surv Ophthalmol 1978;23:26 –34. 11. Cerami A, Stevens VJ, Monnie VM. Role of nonenzymatic glycosylation in the development of the sequelae of diabetes mellitus. Metabolism 1979;28:431–7. 12. Skalka HW, Prachal JT. The effect of diabetes mellitus and diabetic therapy on cataract formation. Ophthalmology 1991; 88:117–25.
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ABSTRACT: This is a report of a case of the development of acute bilateral cataracts in a diabetic patient. A 28year-old man presented to the emergency room with a 4-day history of acutely diminished vision. The patient had a recent history of hyperglycemia. On examination, vision was noted to be count-fingers bilaterally; both lenses were intumescent with dense cortical opacities.
After 4 weeks, the cataracts had not resolved and cataract extraction surgery was performed, with improvement of the patient’s vision. A review of the mechanism of this infrequent presentation of cataract is presented. KEY INDEXING TERMS: Diabetes; Cataract; Hyperglycemia; Hexokinase; Aldehyde reductase. [Am J Med Sci 2005;329(2):99–101.]
O
After examination and discussion, the patient was diagnosed with bilateral acute diabetic cataracts, a rare presentation of diabetic cataract that develops dramatically in less than 1 day.
cular manifestations of diabetes mellitus include disorders of the retina, lens, cornea, and extraocular muscles. A case of acute diabetic cataract is presented with successful surgical management. Case Report
A 28-year-old man presented to the emergency room with a 4-day history of acute loss of vision bilaterally. The patient stated that he enjoyed good vision until waking with severely decreased vision in both eyes accompanied by photophobia, dryness, and redness. He had no significant ocular history and denied any recent trauma or visual symptoms prior to the sudden loss of vision. He denied any recent illnesses. His past medical history was significant for diabetes mellitus type 2 diagnosed 1 year earlier and bipolar disorder. Fasting blood sugar reportedly averaged 200 mg/dL but was 474 mg/dL upon presentation in the emergency department. His medications included Glucophage, insulin, venlafaxine (Effexor), simvastatin (Zocor), lamotrigine (Lomictal), quetiapine fumarate (Seroquel), zolpidem tartrate (Ambien), and clonazepam (Klonopin). At initial examination (Figure 1), the patient’s visual acuity was counting fingers at 4 inches OU. Pupil examination findings were normal, as was intraocular pressure. Slit-lamp examination was notable for mild conjunctival injection and shallow anterior chambers. Lenses were extremely intumescent with dense cortical opacities and prominent water clefts (Figure 2). There was no view of the retina. B-scan ultrasonogram was unremarkable. The patient was followed for 4 weeks, with no change in examination findings. Cataract extraction was then performed in the left eye. The lens was removed with phacoemulsification and a posterior chamber intraocular lens was implanted. The patient was seen on postoperative day 1; vision was improved to 20/40 OS (left eye). Examination of the retina revealed an apparently healthy retina with no sign of retinopathy. The patient did not keep subsequent appointments and was lost to follow-up.
From the University of Missouri-Kansas City (ARF, RG, YS) and the Eye Foundation of Kansas City (RK), Kansas City, Missouri. Submitted March 17, 2004; accepted July 28, 2004. Correspondence: Rohit Krishna, MD, University of MissouriKansas City, Department of Ophthalmology, Eye Foundation of Kansas City, 2300 Holmes Street, Kansas City, MO 64108 (Email: [email protected]). THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES
Discussion Diabetes mellitus, a disorder of carbohydrate metabolism in which sugars are not properly oxidized because of lack of insulin or insulin resistance, may lead to numerous systemic and ocular complications. Ocular manifestations of the disease include retinopathy, extraocular muscle paresis, corneal compromise, and cataracts.1 The association between cataract formation and diabetes mellitus is well described in the literature,2 and the incidence of cataract formation is usually higher in patients with a longer duration of disease. Although acceleration of typical senile cataracts is commonly seen in patients with diabetes, true acute diabetic cataracts usually occur in patients younger than 40 years of age. They are rare, with a prevalence of less than 1% in diabetic patients. They are commonly referred to as “juvenile” diabetic cataracts.3 Cataracts brought about by acute hyperglycemia may arise quickly, as seen in our patient, even within hours or days. Within that time, these lenses can progress from clear to completely opaque.4 Treatment of acute hyperglycemia has been associated with arrest, partial reversal, and even further progression of the cataract. If no permanent lenticular cell damage occurs, the cataractous changes may rarely regress; however, complete reversal is rare.5 Acute diabetic cataracts are typically bilateral and morphologically include anterior or posterior subcapsular “snowflake opacities,” fine stellate needle-shaped cortical opacities, and subcapsular vacuoles and clefts.6 Although numerous mechanisms have been proposed for the development of acute diabetic cata99
Sudden Bilateral Visual Loss in a Diabetic Man
Figure 1. A 28-year-old man with acute, bilateral dense cortical cataracts.
racts, overloading of the hexokinase pathway and subsequent routing of substrate into the alternate aldose reductase pathway is the favored theory. The hexokinase pathway is the main route of glucose metabolism within the lens. However, with poorly managed glycemic control, this enzyme becomes saturated and aldose reductase, an enzyme with lesser affinity for glucose than hexokinase, is able to convert the extra glucose into the sugar alcohol sorbitol and eventually fructose. Neither sorbitol nor fructose is able to penetrate cell membranes, so once formed they accumulate to high levels intracellularly within the lens, creating a hyperosmolar state. The resulting osmotic influx of fluid causes swelling of the lens fibers; at this point, these changes are potentially reversible.7 These mechanisms can initially lead to refractive changes. A myopic shift is observed as intracellular sugar concentrations rise. As blood sugar levels decrease in response to therapy, reverse flow is thought to take place, causing a transitory hyperopic shift.8 Long-term maintenance of lens clarity is dependent on low intracellular water concentration. Transport pumps within the cell membrane of the lens actively exchange ions between the lens cells and aqueous humor. Water passively moves across the cell membranes following Na⫹, maintaining a relative state of dehydration. The intracellular
swelling initiated by the retention of sorbitol and fructose increases permeability to cations and eventually overruns the Na⫹-K⫹ pump’s ability to maintain normal ratios across the cell membrane. This further worsens the hyperosmolar state, resulting in protein denaturation and increased opacification, which becomes irreversible as the swollen lens fibers rupture.7,9 Interestingly, numerous reports of cataract formation after treatment of hyperglycemia have been reported in the literature. These reports of cataract formation in the hypo- and euglycemic patient seem to contradict the concept of hyperosmolar swelling as the sole cause of diabetic cataract formation and have led to the postulation that the destabilization of hexokinase by glucose deprivation may be a key element of hypoglycemic cataract formation. Thus, maintenance of normal blood sugar and prevention of repeated fluctuations in either direction probably reduces the risk of cataract formation.10 Glycosylation, a known risk factor for the development of diabetic retinopathy, has also been studied in the incidence of cataract formation. At one time it was hypothesized that glycosylation of lens proteins increased their susceptibility to light scattering effects and brunescence.9 However, studies since have shown no such correlation.11 Additionally, the HbA1C, a measure of bloodstream glycosylation, does not appear to correlate with the development of diabetic cataracts and thus cannot be relied upon in predicting patients at risk for their development.12 Conclusion Although senile cataracts commonly occur at an earlier age and progress more rapidly in diabetic patients, irreversible development of diabetic cataract acutely, as seen in our patient, is a rarely reported entity. It is probable that the development of acute cataracts in our patient was exacerbated by elevated glucose levels beyond the normal range. The mechanism of his cataract formation most likely adheres to the physiologic and biochemical principles reviewed, dealing with the aldose reductase pathway and osmotic influx of water into a hyperosmotic lens. The irreversibility of his cataract, which required surgical intervention, is a reflection of the severity of this disease. Surgical removal of the cataractous lens can result in successful visual outcomes. References
Figure 2. Slit-lamp photograph of same patient, right eye. The lens is entirely opacified.
100
1. Dorland WA, editor. Dorland’s illustrated medical dictionary. Philadelphia (PA): Saunders; 1981.
February 2005 Volume 329 Number 2
Florkowski et al.
2. Bradbury MJ, Aiello LM. In: Kozak G, editor. Diabetic eye disease in clinical diabetes mellitus, 1st ed. Philadelphia (PA): WB Saunders; 1982. p. 256 –7. 3. Vinding T, Nielsen NV. Two cases of acutely developed cataract in diabetes mellitus. Acta Ophthalmol 1984;62:373–7. 4. Roberts W. Rapid lens changes in diabetes mellitus. Am J Ophthalmol 1950;33:1283–5. 5. Gelvin JB, Thonn VA. The formation and reversal of acute cataracts in diabetes mellitus. J Am Optom Assoc 1993;64: 471– 4. 6. Caird FI, Prie A, Ramsell TG. Diabetes and the eye. Oxford (UK): Blackwell Scientific Publications; 1969. p. 127–34. 7. Kinoshita JH. Mechanisms initiating cataract formation. Invest Ophthalmol Vis Sci 1974;13:713–25.
THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES
8. Duke-Elder WS. The neurology of vision motor and optical anomalies. In: Duke-Elder WS, editor. Textbook of ophthalmology, vol. 4. St. Louis (MO): CV Mosby; 1949. p. 4364 – 6. 9. Kador PF, Kinoshita JH. Diabetic and galactosaemic cataracts. In: Human cataract formation. Ciba Foundation Symposium 106. London (UK): Pitman; 1984. p. 110 –31. 10. Chylach LT, Cheng HM. Sugar metabolism in the crystaline lens. Surv Ophthalmol 1978;23:26 –34. 11. Cerami A, Stevens VJ, Monnie VM. Role of nonenzymatic glycosylation in the development of the sequelae of diabetes mellitus. Metabolism 1979;28:431–7. 12. Skalka HW, Prachal JT. The effect of diabetes mellitus and diabetic therapy on cataract formation. Ophthalmology 1991; 88:117–25.
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