Orthokeratosis is

hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins & Cotran Patholo ...

without

parakeratosis Parakeratosis is a mode of keratinization characterized by the retention of nuclei in the stratum corneum. In mucous membranes, parakeratosis is normal.Kumar, Vinay; Fausto, Nelson; Abbas, Abul (2010) ''Robbins & Cotran Pathologic Basis of Disease' ...

. No nucleus is seen in the cells. There is also formation of an anuclear keratin layer, as in the normal epidermis.

References

Dermatologic terminology {{Cutaneous-condition-stub