Table 5.

Changes of optical density differences in particular groups—results after 2 year (baseline vs. follow-up 2).

Optical density difference	Group						p*
	I		II		III
	n	%	n	%	n	%	I vs. II	I vs. III	II vs. III
Decrease	32	18.0	78	38.0	74	45.4	< 0.001	< 0.001	NS (0.19)
No change	9	5.1	15	7.3	16	9.8	0.48	NS (0.14)	NS (0.50)
Increase	137	77.0	112	54.6	73	44.8	< 0.001	< 0.001	NS (0.08)

*p < 0.05 significant.