Subretinal demarcation lines (The water marks) indicate:

Ans. b. Old rhegmatogenous retinal detachment (Ref: Yanoff and Duker 4/e p651 Kanski 7/e p687; Khurana 4/e p275-279)Suhretinal demarcation lines (The water marks) indicate old rhegmatogenous retinal detachment.'In chronic cases of Rhegmatogenous retinal detachment, a demarcation pigment line suggests the presence of fluid egress via an outer wall hole into the subretinal space, creating a detachment.'- Yanoff and Duker 4/e p651Rhegmatogenous Retinal DetachmentA rhegmatogenous retinal detachment (RRD) occurs when a tear in the retina leads to fluid accumulation with a separation of the neurosensory retina from the underlying retinal pigment epitheliumQ.MC type of retinal detachmentQIn chronic cases of Rhegmatogenous retinal detachment, a demarcation pigment line suggests the presence of fluid egress via an outer wall hole into the subretinal space, creating a detachmentQ.Pathophysiology:Vitreoretinal traction is responsible for the occurrence of most RRD.As the vitreous becomes more syneretic (liquefied) with age, a posterior vitreous detachment (PVD) occurs.In most eyes, the vitreous gel separates from the retina without any sequelae. However, in certain eyes, strong vitreoretinal adhesions are present and the occurrence of a PVD can lead to a retinal tear formation; then, fluid from the liquefied vitreous can seep under the tear, leading to a retinal detachmentQ.The location of the RRD generally predicts the most likely locations of the retinal break(s).Retinal breaks are usually present superiorly within the area of detachmentQ.Predisposing Factors for Rhegmatogenous Retinal Detachment* MyopiaQ* Aphakia or pseudophakiaQ* Vitroretinal degenerationQ* Lattice degenerationQ* Snail track degenerationQ* Diffuse chorioretinal atrophyQ* Macular holesQ* Posterior vitreous degenerationQ* Trauma* Vitreous loss during cataract surgeryClinical Features:Early symptoms; Sudden appearance of floaters, frequently associated with fleeting photopsias (flashes), more noticeable in the dark and following rotary eye movementsQSubclinical RRDs can be asymptomatic, and are associated with limited dissection of subretinal fluid (less than two disc diameters from the break).Rarely, but especially in young myopes, slowly progressive asymptomatic retinal detachments develop without PVD, this most commonly occurs temporally and inferiorly and secondary to atrophic holes in lattice degenerationQ.Due to the persistent attachment of the vitreous at the vitreous base after the PVD. most retinal breaks occur anteriorlyQ.The accumulation of subretinal fluid produces relative scotomata that, when the detachment progresses posterior to the equator, can be symptomatic with loss of peripheral vision, producing the sensation that 'curtain is falling' over the visual field.Central visual acuity is lost when subretinal fluid passes beneath the maculaQ.Diagnosis:The majority of causative retinal breaks associated with RRD are found by binocular stereoscopic examination of the entire retina, with scleral indentation of the peripheral retinaQ.Areas of retinal detachment are recognized by elevation of the neural retina from the RPE and loss of pigment epithelial and choroidal detail beneath the elevated retinaQ.In pseudophakic RRD, all breaks may not be visible because of very small tears: and adjunctive treatment maneuvers may be employed at the time of RRD repair (e.g., 360 degree circumferential laser retinopexy).In eyes with opaque media, the presence of a retinal detachment is usually determined ultrasonographically.Treatment:Surgery is the mainstay.Sealing of the break is done followed by pneumatic retinopexy using sulphur hexafluorideQ.