Corneal confocal microscopy in a healthy Brazilian sample

This study aims to evaluate the characteristics of the corneal sub-basal plexus by performing in vivo confocal microscopy of healthy Brazilians to provide reference values for the Brazilian population.

Method

This study is an observational, cross-sectional, descriptive study comparing corneas from 55 healthy Brazilian individuals across the age span of 20-70 years.

Results

The average number of fibers was 5.35 ± 1.36, fiber density was 33.4 ± 8.5 fibers per field, and the mean number of Langerhans cells was 5.13 ± 8.10. A correlation between the average number of fibers and age showed an inverse relationship between the number and density of fibers and age for women (p < 0.05). In the multivariate analysis, each annual increase of age showed an average increase of 1.017 (95%CI: 1.008 to 1.026) in the number of Langerhans cells, adjusting for sex and thickness.

Conclusion

Compared to other samples, this Brazilian population showed a higher average number of fibers, though further studies with a larger sample should be performed.

cornea; confocal microscopy; Langerhans cells; fibers; age

Age	Male (n = 25)	Female (n = 30)	Total (n = 55)	p-value

	46.2 ± 13.5	43.9 ± 13.1	44.9 ± 13.2	0.54
Age Category
21-30 years	5 (20%)	6 (20%)	11 (20%)
31-40 years	5 (20%)	6 (20%)	11 (20%)
41-50 years	5 (20%)	8 (27%)	13 (24%)
51-60 years	5 (20%)	5 (16.5%)	10 (18%)
61-70 years	5 (20%)	5 (16.5%)	10 (18%)
Total	25 (100%)	30 (100%)	55 (100%)

CCM¹
# of fibers	5.52 ± 1.2	4.20 ± 1.5	5.35 ± 1.4	0.37
Density of fibers	34.5 ± 7.6	7.68 ± 8.6	33.4 ± 8.5	0.37
Langerhans cells	7.00 ± 10.9	3.57 ± 4.2	5.13 ± 8.1	0.49
Width
Absence	0 (0%)	2 (6.7%)	2 (3.6%)
Thin	6 (24%)	10 (33.3%)	16 (29.1%)
Medium	18 (72%)	17 (56.7%)	35 (63.6%)
Large	1 (4%)	1 (3.3%)	2 (3.6%)
Total	25 (100%)	30 (100%)	55 (100%)
Tortuosity
Absence	0 (0%)	2 (6.7%)	2 (3.6%)
Parallel	11 (44%)	14 (46.7%)	25 (45.5%)
Non-parallel – same direction	13 (52%)	12 (40%)	25 (45.5%)
Non-parallel – no direction	1 (4%)	2.6 (7%)	3 (5.5%)
Total	25 (100%)	30 (100%)	55 (100%)

	Observer 1						Observer 2						Observer 3

	Right eye		Left eye		Total		Right eye		Left eye		Total		Right eye		Left eye		Total

	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%	N	%
Tortuosity*
Absence	4	2	8	3	12	2	5	2	29	10	34	6	0	0	6	2	6	1
Parallel	140	54	128	44	268	49	73	28	101	35	174	32	72	28	107	37	179	32
Not parallel, but in the same direction	104	40	123	42	227	41	132	51	108	37	240	44	157	60	155	53	312	57
Same direction	12	45	31	11	43	8	50	19	52	18	102	18	31	12	22	8	53	10
Total	260	100	290	100	550	100	260	100	290	100	550	100	260	100	290	100	550	100
Thickness*
Absence	4	2	8	3	12	2	5	2	29	10	34	6	1	0	6	2	7	1
Thin	69	26	106	37	175	32	61	24	48	17	109	20	128	49	115	40	243	44
Medium	162	62	165	57	327	60	138	53	129	44	267	48	118	45	130	45	248	45
Large	25	10	11	4	36	6	56	22	84	29	140	26	13	5	39	13	52	10
Total	260	100	290	100	550	100	260	100	290	100	550	100	260	100	290	100	550	100

	Right eye						Left eye						Total

	Conc. (%)		Kappa (95%CI)		Kappa pond.		Conc. (%)		Kappa (95%CI)		Kappa pond.		Conc. (%)		Kappa (95%CI)		Kappa pond.

Tortuosity
Obs 1 & Obs 2	51%		0.250 0.16-0.33		0.314		46%		0.227 0.15-0.30		0.279		48%		0.240 0.18-0.30		0.296
Obs 1 & Obs 3	86%		0.749 0.67-0.82		0.767		84%		0.750 0.68-0.82		0.776		85%		0.750 0.70-0.80		0.774
Obs 2 & Obs 3	56%		0.307 0.22-0.39		0.346		46%		0.225 0.15-0.30		0.276		51%		0.266 0.20-0.32		0.309
Width
Obs 1 & Obs 2	66%		0.433 0.33-0.53		0.509		61%		0.402 0.32-0.48		0.500		64%		0.419 0.36-0.48		0.510
Obs 1 & Obs 3	90%		0.810 0.75-0.88		0.802		88%		0.790 0.72-0.85		0.814		89%		0.803 0.76-0.85		0.812
Obs 2 & Obs 3	66%		0.429 0.33-0.52		0.480		58%		0.359 0.27-0.44		0.470		62%		0.395 0.33-0.45		0.481

Authors	Country	Age range	Sample size	Density	Standard deviation
Patel et al., 2009¹⁰	New Zealand	37 ± 10	31 eyes	25.9	7
Niederer et al., 2007¹¹	New Zealand	45 ± 17	30 eyes	21.6	5.91
Parissi et al., 2013¹²	Norway	88 ± 15	207 eyes	19	5.1
Niederer et al., 2007⁴	New Zealand	38 ± 16	170 eyes	20.3	6.5
Current Study	Brazil	70 ± 21	110 eyes	33.4	8.5

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[1] Correspondence: Osvaldo J. M. Nascimento; Rua Siqueira Campos, 53/1204; 22031-071 Rio de Janeiro RJ, Brasil; E-mail:osvaldo_nascimento@hotmail.com