Computing uveal melanoma basal diameters: a comparative analysis of several novel techniques with improved accuracy

Table 1 Relative insensitivity of our mathematical formula to variations in axial length of the eye

Axial length	Largest basal diameter (by length of single chord measurement)
Axial length	6 mm	8 mm	10 mm	12 mm	14 mm	16 mm	18 mm
21.9 mm (− 2 SD)	6.08	8.19	10.38	12.70	15.19	17.94	21.13
22.8 mm (− 1 SD)	6.07	8.17	10.35	12.64	15.07	17.74	20.75
23.7 mm (average)	6.07	8.16	10.32	12.58	14.98	17.56	20.44
24.6 mm (+ 1 SD)	6.06	8.15	10.30	12.54	14.89	17.42	20.19
25.5 mm (+ 2 SD)	6.06	8.14	10.28	12.49	14.82	17.30	19.98
Maximum difference (− 2 SD to + 2 SD)	0.02	0.05	0.10	0.21	0.37	0.64	1.15
Plaque selection	All same	All same	All same	All same	All same	All same	All same (enucleation)

The implication is that the actual axial length need not be measured, and the population average axial length (23.7 mm) can be substituted
mm, millimeters; SD, standard deviation