642
...
form was decreased proportionally to the increase of total T4. This sequence of changes can be argued because there is an equilibrium between a hormone and its binding proteins.’4 The FT4 index is, in essence, T4xT3 resin uptake. T3 resin uptake is, for practical purposes, taken to represent the fraction of unbound T4, although T3 tracer, is being used. There is no objection to this procedure and it is permissible to use the FT4 index (as an estimate of FT4) for comparison between patients, provided that the affinity characteristics of the binding proteins do not differ between the subjects tested. If serum binding of T4 is increased but serum binding of T3 is not, FT4 index will give (falsely) raised values because the unbound fraction of T4, as estimated with T3 tracer, will not be found to be decreased. Indeed we found that the affinity of T4 for the three thyroid-hormone-binding proteins in the subjects positive for the trait was higher than that in their unaffected relatives. Although the apparent Ka values of the affected and unaffected members are of the same order of magnitude as those reported by others ’20 the differences between the family subgroups are highly significant. The finding that the affinity of T4 for all three binding proteins is increased, not just for one, is remarkable and suggests either that a circulating substance interferes positively with the interaction between T4 and T.B.G., T.B.P.A., and albumin, or that there is a deficiency of a natural occurring inhibitor. These possibilities, however, are speculative and further investigations are necessary. Because T.B.G. and T.B.P.A. capacity and albumin concentration was normal in all the members of both families who had the abnormal thyroid hormone profile, the increased affinity of T4 would have led to increased occupancy of binding sites by T4 and consequently a decreased number of free binding sites. Serum-T3 and serum-rT3 were normal and tracer T3 binding to serum was unaltered (as shown by the T3 resin uptake). If fewer sites for binding of these hormones were available, the affinity of these other iodothyronines for the three serum proteins was, presumably, proportionally increased relative to T4. The results of the turnover studies in the propositi accorded with our in-vitro findings of increased serum binding of T4 with a normal FT4 and normal serum binding of T3 and rT3. The decreased VT4 and increased PT4 are fully explained by increased serum binding of T4 and are of the order described in subjects with idiopathic elevation of serum T.B.G.21 The normal turnover of T4 is consequently expected when FT4 is normal. The frequency in the population of the "euthyroid high total-T4, normal T3 syndrome" is unknown but, from a practical point of view, its existence should be kept in mind in the diagnostic evaluation of thyroid function in patients. We thank Dr C. v. d. Peyl, Juliana Hospital, Terneuzen, and Dr B. A. de Planque, Municipal Hospital, Dordrecht, for the opportunity to study their patients, and Miss B. Engelhard for secretarial assistance.
Requests for reprints should be addressed to G. H.
REFERENCES 1. Turner, J. G., Brownlie, B. E. W., Sadler, W. A. Lancet, 1975, i, 407. 2. Kirkergaard, C. G., Siersbæk-Nielsen, K., Friis, Th., Rogowski, P. ibid. p. 868.
3. Hadden, D. R., McMaster, A., Bell, T. K., Weaver, J. A., Montgomery, D. A. ibid. p. 754. 4. Turner, J. G., Brownlie, B. E., Sadler, W. A., Jensen, C. A. ibid. p. 1292. 5. Button, K. E., Quin, V., Ellis, S. M., Cayley, A. C. D., Miralles, J. M., Brown, B. L., Ekins, R. P. ibid. p. 141. 6. Surks, M. I., Schadlow, A. R., Stock, J. M., Oppenheimer, J. H. J. clin. Invest. 1973, 52, 805. 7. Birkhäuser, M., Burer, Th., Busset, R., Burger, A. Lancet, 1977, ii, 56. 8. Visser, T. J., van den Hout-Goemaat, N. L., Docter, R., Hennemann, G. Neth. J. Med. 1975, 18, 111. 9. Docter, R., Hennemann, G., Bernard, H. F. Israel. J. med. Sci. 1972, 8, 1870. 10. Visser, T. J., Docter, R., Hennemann, G. J. Endocr. 1977, 73, 395. 11. Digulio, W., Michalak, Z., Wemhold, P. A., Hamilton, J. R., Thomas, G. E. J. lab. clin. Med. 1964, 64, 319. 12. Van Welsum, M., Feltkamp, T. E. W., de Vries, M. J., Docter, R., van Zijl, J., Hennemann, G. Br. med. J. 1974, iv, 755. 13. Karlsson, F. A., Wibell, L., Wide, L. New Eng. J. Med. 1977, 296, 1146. 14. Robbins, J., Rall, J. E. Physiol. Rev. 1960, 40, 415. 15. Hennemann, G., Docter, R., Dolman, A. J. clin. Endocr. Metab. 1973, 33, 63. 16. Hennemann, G., Smeulers, J., van der Does, I., Docter, R., Visser, T. J. Acta endocr. Copenh. 1976, 82, 92. 17. Oppenheimer, J. H., Schwartz, H. L., Surks, M. I. J. clin. Endocr. Metab
1975, 41, 319. 18. Oppenheimer, 19. De Groot, L.
J. H., Schwartz, H. L., Surks, M. I. ibid. p. 1172. J., Stanbury, J. B. in The Thyroid and its Diseases; p. 213,
1975. 20. De Groot, L. J., Stanbury, J. B. ibid. p. 64. 21. Nicoloff, J. T., Low, J. C., Dussault, J. H.,
Fisher, D. A. J. clin. Invest. 1972,
51, 473.
Addendum
After
told doctors in our hospital about the synpresented with 3, probably 4, additional similar patients, of whom 3 had been previously treated with antithyroid drugs for supposed hyperthyroidism. If this syndrome turns out to be a common one, some thought should be given to abandoning the FT4 index as a routine screening test for thyroid function and using the measurement of the FT4 instead.
drome,
we
we were
VISUAL DISABILITY AND HOME LIGHTING T. R. CULLINAN E. S. GOULD
J. H. SILVER D. IRVINE
Department of Environmental and Preventive Medicine Medical Research Council Toxicology Unit, St. Bartholomew’s Hospital Medical College, London EC1M 7BE and 43 women (average age 76) attending a low-vision clinic with visual of or less had acuity measurements 6/18 (Snellen) acuity made under standard (measured) hospital conditions, under normal home conditions, and under home conditions with augmented lighting. Median levels of ambient lighting in the home were 1/10 of those in hospital, while levels for reading were 1/7. Augmented lighting at home (a 60 watt bulb in a small adjustable lamp) improved visual acuity in 82% of subjects, restoring all but 11% to the levels achieved in hospital or above. Improvement was unrelated to disease. General levels of lighting are often so poor in the homes of elderly people that the number of people functioning as "blind" is twice what it need be. Simple improvements to lighting would reduce the prevalence of "visual disability" (less than 6/18 Snellen) from 520/100 000 home-based adults to about 300.
Summary
13
men
643 Results
Introduction OF every 100 000 people over 16 years old living at home in England and Wales, 520 have a distance visual acuity of less than 6/18 (Snellen) and are therefore "visually disabled" by W.H.O. criteria.2 80% of the affected people are in their retirement years and half are over 75. Scarcely more than half have ever had a specialist assessment of their eyes, probably because they accept sight loss as one of the penalties of growing old. However, 60% of people who attend an eye clinic apparently see at least slightly better there than at home. This survey finding,’ which mirrored earlier work in Canterbury, suggested that there was a difference in testing conditions between the two places and it seemed likely that the main difference lay in the lighting levels. We describe here an experiment which illustrates this difference.
Subjects
and Methods
Subjects for the study were chosen from patients referred under normal circumstances to the low-vision and refraction clinic at Moorfield’s Eye Hospital between January and May, 1978. Criteria for entry were: (1) best binocular distance visual acuity 6/18 or less (internally illuminated chart); (2) living at home within range of the hospital; U) aged 16 years or more; (4) literate in English, willing and able to complete visual acuity tests. We ensured that the age groups of those included, the different levels of their visual acuity, and the diagnoses of their eye conditions roughly conformed to the pattern found in the whole population.I 13 men and 43 women with visual disability aged 46-91 years (mean 76) were studied. Diagnoses were macular de-
generation (26 patients), cataract (14), myopic degeneration (6), glaucoma (4), and diabetic retinopathy (6). Between-observer and between-instrument (hand-held and internally illuminated charts) validation studies were completed before the trial, and hospital lighting levels were measured for both distance and near vision (surface measurement) with a Hagnar Mark 1 photometer. Each potential subject was assessed for distance and near vision in the manner normally used in the clinic, with standard subjective and objective refraction techniques. Routine presbyopic correction or low vision aid was prescribed to meet reading requirements, but ro advice on illumination was given (unless the subject declined to take part in the study). The purpose of the study "to compare how people see at home and in the clinic" was then explained, and an appointment was made were asked to make no special preparations. All home assessments were made within a few days of the hospital visit by alternate observers who did not know the chnic findings and the aid prescribed. Distance acuity was measured at 3 m, first with a hand-held Snellen card in the best available home lighting (chart luminance measured), then wit1.1 lighting augmented by a simple reading lamp (60 watt bulb) with glare and surface reflections avoided, and finally w’th a portable internally illuminated chart. Each subject wore appropriate corrective lenses. acuities were determined with the subject sitting where he "usually" sat to read, and wearing the spectacles or lovr vision aid used to determine acuities in the clinic. Acuity measurements were made first with normal (measured) illuminance levels and then with the optimal illumination achievable by careful placing of the reading lamp. A sealed package containing any new aids prescribed in the chnic was then opened and instructions given in their use.
Light for Distance Vision Compared with hospital standards, most homes had very poor ambient lighting (fig. 1). For distance acuity testing only 2 achieved clinic lighting levels (200-210 lux); most were far below this, with 9 homes having no more than 10 lux of overhead light. The median home lighting value was 20-30 lux (1/10 of that in hospital): most homes had a central overhead living room light and many had a standard lamp with a heavy shade. Few homes had dark walls but windows were usually hung with net and opaque curtains were half drawn. Passages and stairs were even more poorly lit. The improvement brought about merely by a well directed 60 watt bulb was remarkable. Median lighting at home was brought up to the hospital standard and the lighting remained below 50 lux in only 2 of 53 homes (fig. 2) (in 3 there was no socket available to improve general lighting). Light for Reading Lighting for reading, although better than overhead ambient lighting, was far short of hospital standards before improvement in 52 homes (fig. 3) (in 4 homes there was no socket to improve light for reading in the usual position). The median value (177 lux) was 1/7 that in the hospital-only two homes equalled or exceeded the lowest hospital value. Installing a simple reading lamp (cost 3.00) with a 60 watt bulb, or repositioning a reading lamp already present, improved the lighting tenfold to a median value of 1730 lux (600 lux better than in the hospital); all but 8 of the 56 homes then achieved or exceeded hospital levels (fig. 4, which
for a home visit. Subjects
Fig.
1-usual home
lighting for distance vision.
Reading
Fig. 2-Augmented home lighting for distance vision.
644 and an increase of 50% to 100% above these levels in old people’s homes. In only 2 of the 56 homes studied were these standards achieved in the main living rooms, though 11 came near to the standards for prolonged reading and sewing. In most homes all that was needed to achieve or exceed the standards was a stronger bulb in a better placed lamp or central
longed reading",
light, and advice about lampshades, curtains, and the placing of chairs. The need for a major and expensive change, such as rewiring or renewing sockets or interior decoration, was rare. To change from a 40 watt to a 60 watt
Fig. 3-Usual home lighting for reading.
bulb increases the
cost
of 10 h illumination from
l.lptol.7p. be made between the degree of improved lighting and improvement in acuity (of distance or near vision) for each individual; to do so is to discount the real effects of different eye conditions and to imply that a simple linear model exists for these people. Indeed it was not possible, with the number of patients No correlation
can
entered into the trial, to satisfy the strict limits of the sequential statistical design which required that no more than 10% of subjects would still show a difference in visual acuity when their home lighting was augmented. It was, however, so nearly achieved (standard 95% confidence limits ll%±8%) that there can remain no doubt that the improvement in lighting was the factor of overwhelming importance. The importance of adequate lighting in the homes of elderly people goes beyond reading and other activities. Brocklehurst and his colleagues4 have shown how often visual disability is associated with home accidents in which the femoral neck is fractured, and poor lighting can only add to the hazards. We were particularly concerned about how badly lit were stairs and the passage-
eventually
Fig. 4-Augmented home lighting for reading.
only those homes in which near vision was improved by better lighting-in all others it was N5 with the usual lighting).
shows
Vision
Improving the lighting improved visual acuity. At home 36 (64%) of the 56 subjects had worse distance vision than in the hospital-2/3 showed a difference of two or more Snellen lines. With improved lighting only 15 continued to see more poorly at home than in hospital and in 13 of those the difference improved to no more than one Snellen line. With the internally illuminated chart, however, correlation between home and hospital was far closer-indeed 12 people appeared to see better in their own homes than in the clinic. Improved lighting also made reading easier. 26 (46%) read at a lower level of acuity at home than in hospital but with improved lighting this figure fell to 9 (16%), of whom all but 3 showed no more than one division difference on the "N" card. In all, 46 (82%) of the 56 subjects had improved vision (distance or near or both) with improved lighting. Almost all of the 10 who did not improve had distance vision of less than 3/60. In assessments of distance vision, those with cataracts improved as much as did those with macular degeneration or other diseases; such comparisons were not possible in assessments of reading because 10 of the 14 with cataracts could already read normal print under conditions in their homes. The othei 4 all saw better with improved lighting. Discussion
ways. Our
study suggests that clinic assessment of visual function in elderly people is a poor indication of their function at home. 10 people might have been considered for blind registration on clinic findings, but twice as many were functioning as "blind" at home. If our applicable to the population as a whole, an improvement in lighting alone would reduce the number of people judged to be visually disabled at home2 from
results
520 to near 300 per 100 000 adults.’1 The use of simple hand-held distance and reading cards was validated by our study and there is no reason why district nurses, health visitors, occupational therapists, and others concerned with the home care of the elderly should not use them to discover, with fair accuracy, who might or might not be in need of help. We thank the D.H.S.S. for supporting this project, and Peter Jay for his advice on the measurement of lighting and for lending us the instruments to achieve it. We also thank the consultants at Moorfields Eye Hospital for their encouragement and the patients for their help and hospitality. REFERENCES
Cullinan, T. R. Visually Disabled People in the Community. Health Services Research Unit Report 28 (table 21). Canterbury University, 1977. 2. W.H.O. The Prevention of Blindness. W.H.O. Technical Report Series No. 518. Geneva, 1973. 3. Illuminating Engineering Society. The I.E.S. Code; pp. 73 and 74. London, 1.
1973. 4.
The Illuminating Engineering Society Code (1973) recommends illuminance of 150 lux for "casual read ing", 300 lux for such activities as "sewing and pro
are
Brocklehurst, J. C., Exton-Smith, A. N., Lempert Barber, S. M., Hunt, L., Palmer, M. Fracture of the Femoral Neck—A Two Centre Survey of Aetiological Factors. No. 1 June, 1976. Departments of Geriatric Medicine. University Hospital of South Manchester, and University College Hospital, London.
...
form was decreased proportionally to the increase of total T4. This sequence of changes can be argued because there is an equilibrium between a hormone and its binding proteins.’4 The FT4 index is, in essence, T4xT3 resin uptake. T3 resin uptake is, for practical purposes, taken to represent the fraction of unbound T4, although T3 tracer, is being used. There is no objection to this procedure and it is permissible to use the FT4 index (as an estimate of FT4) for comparison between patients, provided that the affinity characteristics of the binding proteins do not differ between the subjects tested. If serum binding of T4 is increased but serum binding of T3 is not, FT4 index will give (falsely) raised values because the unbound fraction of T4, as estimated with T3 tracer, will not be found to be decreased. Indeed we found that the affinity of T4 for the three thyroid-hormone-binding proteins in the subjects positive for the trait was higher than that in their unaffected relatives. Although the apparent Ka values of the affected and unaffected members are of the same order of magnitude as those reported by others ’20 the differences between the family subgroups are highly significant. The finding that the affinity of T4 for all three binding proteins is increased, not just for one, is remarkable and suggests either that a circulating substance interferes positively with the interaction between T4 and T.B.G., T.B.P.A., and albumin, or that there is a deficiency of a natural occurring inhibitor. These possibilities, however, are speculative and further investigations are necessary. Because T.B.G. and T.B.P.A. capacity and albumin concentration was normal in all the members of both families who had the abnormal thyroid hormone profile, the increased affinity of T4 would have led to increased occupancy of binding sites by T4 and consequently a decreased number of free binding sites. Serum-T3 and serum-rT3 were normal and tracer T3 binding to serum was unaltered (as shown by the T3 resin uptake). If fewer sites for binding of these hormones were available, the affinity of these other iodothyronines for the three serum proteins was, presumably, proportionally increased relative to T4. The results of the turnover studies in the propositi accorded with our in-vitro findings of increased serum binding of T4 with a normal FT4 and normal serum binding of T3 and rT3. The decreased VT4 and increased PT4 are fully explained by increased serum binding of T4 and are of the order described in subjects with idiopathic elevation of serum T.B.G.21 The normal turnover of T4 is consequently expected when FT4 is normal. The frequency in the population of the "euthyroid high total-T4, normal T3 syndrome" is unknown but, from a practical point of view, its existence should be kept in mind in the diagnostic evaluation of thyroid function in patients. We thank Dr C. v. d. Peyl, Juliana Hospital, Terneuzen, and Dr B. A. de Planque, Municipal Hospital, Dordrecht, for the opportunity to study their patients, and Miss B. Engelhard for secretarial assistance.
Requests for reprints should be addressed to G. H.
REFERENCES 1. Turner, J. G., Brownlie, B. E. W., Sadler, W. A. Lancet, 1975, i, 407. 2. Kirkergaard, C. G., Siersbæk-Nielsen, K., Friis, Th., Rogowski, P. ibid. p. 868.
3. Hadden, D. R., McMaster, A., Bell, T. K., Weaver, J. A., Montgomery, D. A. ibid. p. 754. 4. Turner, J. G., Brownlie, B. E., Sadler, W. A., Jensen, C. A. ibid. p. 1292. 5. Button, K. E., Quin, V., Ellis, S. M., Cayley, A. C. D., Miralles, J. M., Brown, B. L., Ekins, R. P. ibid. p. 141. 6. Surks, M. I., Schadlow, A. R., Stock, J. M., Oppenheimer, J. H. J. clin. Invest. 1973, 52, 805. 7. Birkhäuser, M., Burer, Th., Busset, R., Burger, A. Lancet, 1977, ii, 56. 8. Visser, T. J., van den Hout-Goemaat, N. L., Docter, R., Hennemann, G. Neth. J. Med. 1975, 18, 111. 9. Docter, R., Hennemann, G., Bernard, H. F. Israel. J. med. Sci. 1972, 8, 1870. 10. Visser, T. J., Docter, R., Hennemann, G. J. Endocr. 1977, 73, 395. 11. Digulio, W., Michalak, Z., Wemhold, P. A., Hamilton, J. R., Thomas, G. E. J. lab. clin. Med. 1964, 64, 319. 12. Van Welsum, M., Feltkamp, T. E. W., de Vries, M. J., Docter, R., van Zijl, J., Hennemann, G. Br. med. J. 1974, iv, 755. 13. Karlsson, F. A., Wibell, L., Wide, L. New Eng. J. Med. 1977, 296, 1146. 14. Robbins, J., Rall, J. E. Physiol. Rev. 1960, 40, 415. 15. Hennemann, G., Docter, R., Dolman, A. J. clin. Endocr. Metab. 1973, 33, 63. 16. Hennemann, G., Smeulers, J., van der Does, I., Docter, R., Visser, T. J. Acta endocr. Copenh. 1976, 82, 92. 17. Oppenheimer, J. H., Schwartz, H. L., Surks, M. I. J. clin. Endocr. Metab
1975, 41, 319. 18. Oppenheimer, 19. De Groot, L.
J. H., Schwartz, H. L., Surks, M. I. ibid. p. 1172. J., Stanbury, J. B. in The Thyroid and its Diseases; p. 213,
1975. 20. De Groot, L. J., Stanbury, J. B. ibid. p. 64. 21. Nicoloff, J. T., Low, J. C., Dussault, J. H.,
Fisher, D. A. J. clin. Invest. 1972,
51, 473.
Addendum
After
told doctors in our hospital about the synpresented with 3, probably 4, additional similar patients, of whom 3 had been previously treated with antithyroid drugs for supposed hyperthyroidism. If this syndrome turns out to be a common one, some thought should be given to abandoning the FT4 index as a routine screening test for thyroid function and using the measurement of the FT4 instead.
drome,
we
we were
VISUAL DISABILITY AND HOME LIGHTING T. R. CULLINAN E. S. GOULD
J. H. SILVER D. IRVINE
Department of Environmental and Preventive Medicine Medical Research Council Toxicology Unit, St. Bartholomew’s Hospital Medical College, London EC1M 7BE and 43 women (average age 76) attending a low-vision clinic with visual of or less had acuity measurements 6/18 (Snellen) acuity made under standard (measured) hospital conditions, under normal home conditions, and under home conditions with augmented lighting. Median levels of ambient lighting in the home were 1/10 of those in hospital, while levels for reading were 1/7. Augmented lighting at home (a 60 watt bulb in a small adjustable lamp) improved visual acuity in 82% of subjects, restoring all but 11% to the levels achieved in hospital or above. Improvement was unrelated to disease. General levels of lighting are often so poor in the homes of elderly people that the number of people functioning as "blind" is twice what it need be. Simple improvements to lighting would reduce the prevalence of "visual disability" (less than 6/18 Snellen) from 520/100 000 home-based adults to about 300.
Summary
13
men
643 Results
Introduction OF every 100 000 people over 16 years old living at home in England and Wales, 520 have a distance visual acuity of less than 6/18 (Snellen) and are therefore "visually disabled" by W.H.O. criteria.2 80% of the affected people are in their retirement years and half are over 75. Scarcely more than half have ever had a specialist assessment of their eyes, probably because they accept sight loss as one of the penalties of growing old. However, 60% of people who attend an eye clinic apparently see at least slightly better there than at home. This survey finding,’ which mirrored earlier work in Canterbury, suggested that there was a difference in testing conditions between the two places and it seemed likely that the main difference lay in the lighting levels. We describe here an experiment which illustrates this difference.
Subjects
and Methods
Subjects for the study were chosen from patients referred under normal circumstances to the low-vision and refraction clinic at Moorfield’s Eye Hospital between January and May, 1978. Criteria for entry were: (1) best binocular distance visual acuity 6/18 or less (internally illuminated chart); (2) living at home within range of the hospital; U) aged 16 years or more; (4) literate in English, willing and able to complete visual acuity tests. We ensured that the age groups of those included, the different levels of their visual acuity, and the diagnoses of their eye conditions roughly conformed to the pattern found in the whole population.I 13 men and 43 women with visual disability aged 46-91 years (mean 76) were studied. Diagnoses were macular de-
generation (26 patients), cataract (14), myopic degeneration (6), glaucoma (4), and diabetic retinopathy (6). Between-observer and between-instrument (hand-held and internally illuminated charts) validation studies were completed before the trial, and hospital lighting levels were measured for both distance and near vision (surface measurement) with a Hagnar Mark 1 photometer. Each potential subject was assessed for distance and near vision in the manner normally used in the clinic, with standard subjective and objective refraction techniques. Routine presbyopic correction or low vision aid was prescribed to meet reading requirements, but ro advice on illumination was given (unless the subject declined to take part in the study). The purpose of the study "to compare how people see at home and in the clinic" was then explained, and an appointment was made were asked to make no special preparations. All home assessments were made within a few days of the hospital visit by alternate observers who did not know the chnic findings and the aid prescribed. Distance acuity was measured at 3 m, first with a hand-held Snellen card in the best available home lighting (chart luminance measured), then wit1.1 lighting augmented by a simple reading lamp (60 watt bulb) with glare and surface reflections avoided, and finally w’th a portable internally illuminated chart. Each subject wore appropriate corrective lenses. acuities were determined with the subject sitting where he "usually" sat to read, and wearing the spectacles or lovr vision aid used to determine acuities in the clinic. Acuity measurements were made first with normal (measured) illuminance levels and then with the optimal illumination achievable by careful placing of the reading lamp. A sealed package containing any new aids prescribed in the chnic was then opened and instructions given in their use.
Light for Distance Vision Compared with hospital standards, most homes had very poor ambient lighting (fig. 1). For distance acuity testing only 2 achieved clinic lighting levels (200-210 lux); most were far below this, with 9 homes having no more than 10 lux of overhead light. The median home lighting value was 20-30 lux (1/10 of that in hospital): most homes had a central overhead living room light and many had a standard lamp with a heavy shade. Few homes had dark walls but windows were usually hung with net and opaque curtains were half drawn. Passages and stairs were even more poorly lit. The improvement brought about merely by a well directed 60 watt bulb was remarkable. Median lighting at home was brought up to the hospital standard and the lighting remained below 50 lux in only 2 of 53 homes (fig. 2) (in 3 there was no socket available to improve general lighting). Light for Reading Lighting for reading, although better than overhead ambient lighting, was far short of hospital standards before improvement in 52 homes (fig. 3) (in 4 homes there was no socket to improve light for reading in the usual position). The median value (177 lux) was 1/7 that in the hospital-only two homes equalled or exceeded the lowest hospital value. Installing a simple reading lamp (cost 3.00) with a 60 watt bulb, or repositioning a reading lamp already present, improved the lighting tenfold to a median value of 1730 lux (600 lux better than in the hospital); all but 8 of the 56 homes then achieved or exceeded hospital levels (fig. 4, which
for a home visit. Subjects
Fig.
1-usual home
lighting for distance vision.
Reading
Fig. 2-Augmented home lighting for distance vision.
644 and an increase of 50% to 100% above these levels in old people’s homes. In only 2 of the 56 homes studied were these standards achieved in the main living rooms, though 11 came near to the standards for prolonged reading and sewing. In most homes all that was needed to achieve or exceed the standards was a stronger bulb in a better placed lamp or central
longed reading",
light, and advice about lampshades, curtains, and the placing of chairs. The need for a major and expensive change, such as rewiring or renewing sockets or interior decoration, was rare. To change from a 40 watt to a 60 watt
Fig. 3-Usual home lighting for reading.
bulb increases the
cost
of 10 h illumination from
l.lptol.7p. be made between the degree of improved lighting and improvement in acuity (of distance or near vision) for each individual; to do so is to discount the real effects of different eye conditions and to imply that a simple linear model exists for these people. Indeed it was not possible, with the number of patients No correlation
can
entered into the trial, to satisfy the strict limits of the sequential statistical design which required that no more than 10% of subjects would still show a difference in visual acuity when their home lighting was augmented. It was, however, so nearly achieved (standard 95% confidence limits ll%±8%) that there can remain no doubt that the improvement in lighting was the factor of overwhelming importance. The importance of adequate lighting in the homes of elderly people goes beyond reading and other activities. Brocklehurst and his colleagues4 have shown how often visual disability is associated with home accidents in which the femoral neck is fractured, and poor lighting can only add to the hazards. We were particularly concerned about how badly lit were stairs and the passage-
eventually
Fig. 4-Augmented home lighting for reading.
only those homes in which near vision was improved by better lighting-in all others it was N5 with the usual lighting).
shows
Vision
Improving the lighting improved visual acuity. At home 36 (64%) of the 56 subjects had worse distance vision than in the hospital-2/3 showed a difference of two or more Snellen lines. With improved lighting only 15 continued to see more poorly at home than in hospital and in 13 of those the difference improved to no more than one Snellen line. With the internally illuminated chart, however, correlation between home and hospital was far closer-indeed 12 people appeared to see better in their own homes than in the clinic. Improved lighting also made reading easier. 26 (46%) read at a lower level of acuity at home than in hospital but with improved lighting this figure fell to 9 (16%), of whom all but 3 showed no more than one division difference on the "N" card. In all, 46 (82%) of the 56 subjects had improved vision (distance or near or both) with improved lighting. Almost all of the 10 who did not improve had distance vision of less than 3/60. In assessments of distance vision, those with cataracts improved as much as did those with macular degeneration or other diseases; such comparisons were not possible in assessments of reading because 10 of the 14 with cataracts could already read normal print under conditions in their homes. The othei 4 all saw better with improved lighting. Discussion
ways. Our
study suggests that clinic assessment of visual function in elderly people is a poor indication of their function at home. 10 people might have been considered for blind registration on clinic findings, but twice as many were functioning as "blind" at home. If our applicable to the population as a whole, an improvement in lighting alone would reduce the number of people judged to be visually disabled at home2 from
results
520 to near 300 per 100 000 adults.’1 The use of simple hand-held distance and reading cards was validated by our study and there is no reason why district nurses, health visitors, occupational therapists, and others concerned with the home care of the elderly should not use them to discover, with fair accuracy, who might or might not be in need of help. We thank the D.H.S.S. for supporting this project, and Peter Jay for his advice on the measurement of lighting and for lending us the instruments to achieve it. We also thank the consultants at Moorfields Eye Hospital for their encouragement and the patients for their help and hospitality. REFERENCES
Cullinan, T. R. Visually Disabled People in the Community. Health Services Research Unit Report 28 (table 21). Canterbury University, 1977. 2. W.H.O. The Prevention of Blindness. W.H.O. Technical Report Series No. 518. Geneva, 1973. 3. Illuminating Engineering Society. The I.E.S. Code; pp. 73 and 74. London, 1.
1973. 4.
The Illuminating Engineering Society Code (1973) recommends illuminance of 150 lux for "casual read ing", 300 lux for such activities as "sewing and pro
are
Brocklehurst, J. C., Exton-Smith, A. N., Lempert Barber, S. M., Hunt, L., Palmer, M. Fracture of the Femoral Neck—A Two Centre Survey of Aetiological Factors. No. 1 June, 1976. Departments of Geriatric Medicine. University Hospital of South Manchester, and University College Hospital, London.
