Ocular Tumours Ocular Diseases

7.2.8 Retinal Detachment

The฀question฀of฀an฀association฀with฀smoking฀was฀pursued฀in฀a฀study฀in฀198฀patients฀with฀reti- nal฀detachment.฀It฀was฀found฀that฀the฀relative฀risk฀for฀retinal฀detachment฀was฀increased฀age- dependently฀by฀the฀presence฀of฀myopia,฀but฀was฀decreased฀by฀current฀smoking฀RR฀=฀0.5;฀ 95฀CI:฀0.3–0.8฀ [188] .

7.3 Ears, Oral Cavity and Larynx

7.3.1 Harmful Effects on the Ears

The฀literature฀contains฀only฀a฀small฀number฀of฀publications฀on฀the฀effects฀of฀smoking฀on฀ hearing,฀although฀it฀can฀probably฀be฀assumed฀that฀blood฀low฀in฀the฀middle฀and฀inner฀ear฀is฀ comparable฀with฀that฀in฀the฀CNS฀and฀that฀hypoxaemic฀states฀together฀with฀microcirculatory฀ changes฀raised฀ibrinogen,฀etc.฀are฀causally฀linked฀with฀the฀harmful฀effects฀of฀smoking฀ [189] .฀According฀to฀a฀study฀in฀163฀patients฀with฀sudden฀deafness,฀smokers฀also฀had฀signii- cantly฀more฀risk฀factors฀for฀coronary฀heart฀disease฀compared฀with฀a฀healthy฀control฀group฀ [190] .฀ Similarly,฀ in฀ 2,348฀ patients฀ with฀ noise-induced฀ hearing฀ loss,฀ the฀ relative฀ risks฀ for฀ smokers฀were฀signiicantly฀elevated฀ever-smoker:฀OR฀=฀1.27,฀p฀=฀0.02;฀current฀smoker:฀ OR฀=฀1.39,฀p฀=฀0.002฀compared฀with฀never-smokers,฀and฀associations฀were฀even฀detected฀ with฀the฀number฀of฀pack-years฀of฀smoking฀ [191] .฀In฀a฀further฀experimental฀series,฀the฀hearing฀ of฀smokers฀and฀non-smokers฀was฀compared,฀following฀adjustment฀for฀other฀factors:฀current฀ smokers฀were฀1.69฀times฀as฀likely฀to฀have฀hearing฀loss฀as฀non-smokers฀ [192] .฀Compared฀with฀ non-exposed฀persons,฀passive฀smokers฀who฀lived฀with฀a฀smoker฀were฀also฀found฀to฀be฀at฀ increased฀risk฀for฀hearing฀loss฀OR฀=฀1.94;฀CI:฀1.01–3.74฀ [192] .฀It฀has฀not฀yet฀been฀fully฀ established฀whether฀auditory฀damage฀occurs฀primarily฀in฀the฀high-frequency฀range฀ [193] .

7.3.2 Changes in the Oral Cavity

All฀tobacco฀consumption฀i.e.฀including฀chewing฀tobacco฀and฀especially฀cigarette฀smoking฀ produces฀changes฀in฀the฀oral฀cavity,฀for฀example,฀mucosal฀changes฀in฀the฀form฀of฀gingivitis฀ [194],฀[195] ฀and฀increased฀tooth฀loss฀ [194,฀196–198] .฀Periodontal฀diseases฀are฀disproportion- ately฀prevalent฀in฀smokers฀ [199–202] .฀In฀the฀USA,฀80฀of฀all฀adult฀cases฀of฀periodontal฀dis- ease฀can฀be฀associated฀with฀smoking฀ [203] .฀Acute฀ulcerative฀gingivitis฀as฀a฀consequence฀of฀ smoking฀has฀been฀known฀for฀more฀than฀50฀years฀ [194] :฀irstly,฀local฀lesions฀are฀produced฀on฀ the฀mucosal฀surface฀by฀the฀tar฀and฀other฀smoke฀products;฀and฀secondly,฀plaque฀formation฀with฀ bacterial฀colonisation฀is฀encouraged฀ [204] .฀Many฀of฀the฀processes฀involved฀have฀still฀to฀be฀ elucidated.฀However,฀it฀has฀been฀demonstrated฀that฀smokers฀have฀reduced฀salivary฀IgA฀and฀ IgG฀antibody฀levels,฀indicative฀of฀an฀immunosuppressive฀effect฀ [205] .฀In฀addition,฀nicotine฀has฀ been฀reported฀to฀inhibit฀the฀proliferation฀of฀osteoblasts฀in฀vitro฀ [206] ฀and฀to฀reduce฀the฀gingival฀ circulation฀ [207] ,฀although฀these฀indings฀need฀to฀be฀conirmed฀in฀further฀investigations. Increased฀plaque฀formation฀is฀a฀proven฀inding฀among฀smokers฀ [208] ,฀and฀this฀leads฀to฀ increased฀bacterial฀colonisation฀of฀the฀oral฀cavity฀and฀gingival฀region฀ [209] ฀with฀all฀the฀ attendant฀consequences.฀Furthermore,฀melanosis฀of฀the฀tongue฀black฀hairy฀tongue฀and฀of฀ the฀ oral฀ mucosa฀ may฀ result฀ from฀ the฀ pigmentation฀ of฀ basal฀ keratinocytes฀ [210] .฀ These฀ changes฀are฀reversible฀on฀smoking฀cessation.฀As฀a฀result฀of฀the฀thermal฀insult฀of฀smoke,฀ pipe฀ smokers฀ often฀ display฀ stomatitis฀ or฀ smoker’s฀ palate฀ [211] ,฀ a฀ condition฀ that฀ may฀ undergo฀transformation฀to฀a฀precancerous฀lesion฀in฀rare฀cases. With฀a฀consumption฀of฀20฀cigarsday฀for฀13฀years,฀Sigmund฀Freud฀may฀serve฀as฀a฀typi- cal฀example:฀he฀developed฀leukoplakia฀with฀recurring฀oral฀cancers,฀for฀which฀he฀had฀to฀ undergo฀surgery฀on฀numerous฀occasions.฀Despite฀having฀to฀wear฀a฀prosthetic฀plate฀in฀his฀ upper฀and฀lower฀jaw,฀he฀continued฀to฀smoke฀persistently฀until฀his฀death. Smoking฀encourages฀discolouration฀of฀the฀teeth฀and฀abrasion฀especially฀in฀pipe฀smok- ers฀or฀users฀of฀chewing฀tobacco.฀In฀association฀with฀tooth฀loss,฀these฀changes฀ultimately฀ lead฀to฀occlusive฀disturbances฀ [211] .฀Such฀indings฀are฀encountered฀more฀frequently฀in฀the฀ USA฀ than฀ in฀ Europe,฀ particularly฀ since฀ 10–16฀ million฀ US฀ Americans฀ use฀ smokeless฀ tobacco฀as฀an฀alternative฀to฀smoking฀cigarettes฀ [212] . Compared฀with฀non-exposed฀children,฀children฀passively฀exposed฀to฀maternal฀smoking฀ are฀found฀to฀be฀at฀increased฀risk฀for฀the฀development฀of฀caries฀OR฀=฀1.54฀vs.฀1.06;฀p฀฀0.05฀ [213] .

7.3.3 Oral and Laryngeal Cancer

More฀than฀9฀out฀of฀10฀oral฀cavity฀cancers฀in฀men฀and฀6฀out฀of฀10฀in฀women฀are฀caused฀by฀ smoking,฀while฀alcohol฀has฀been฀identiied฀as฀the฀strongest฀additional฀risk฀factor฀ [214] .฀ Compared฀ with฀ non-smokers,฀ the฀ relative฀ risk฀ in฀ smokers฀ is฀ increased฀ by฀ 2-฀ to฀ 18-fold฀ [215] ,฀the฀increase฀being฀dependent฀on฀the฀number฀of฀cigarettes฀smoked฀daily฀ [216] .฀The฀ risk฀of฀cancer฀development฀declines฀just฀a฀few฀years฀after฀smoking฀cessation฀ [217] ,฀in฀one฀ study฀by฀50฀after฀3–5฀years฀of฀smoking฀abstinence฀ [216] .฀The฀eficacy฀of฀radiation฀therapy฀ in฀such฀tumours฀is฀considerably฀reduced฀where฀patients฀continue฀to฀smoke฀ [218] .฀Likewise,฀ 8฀out฀of฀10฀cases฀of฀laryngeal฀cancer฀are฀caused฀by฀cigarette฀smoking฀ [219] ,฀and฀the฀causal฀ relationship฀has฀been฀conirmed฀by฀numerous฀epidemiological฀and฀clinical฀studies฀ [220] .฀ The฀risk฀of฀laryngeal฀cancer฀is฀also฀associated฀with฀the฀number฀of฀cigarettes฀smoked฀ [220] .฀ For฀every฀incremental฀increase฀in฀pack-years฀of฀smoking,฀there฀is฀a฀small฀but฀measurable฀ increase฀in฀the฀odds฀that฀a฀patient’s฀laryngeal฀cancer฀will฀already฀be฀stage฀III฀or฀IV฀at฀initial฀ diagnosis฀ [221] .฀The฀bidi฀cigarettes฀commonly฀smoked฀in฀India฀constitute฀a฀particular฀dan- ger:฀ compared฀ with฀ non-smokers,฀ smokers฀ of฀ 20฀ bidi฀ cigarettesday฀ have฀ a฀ 12.68-fold฀ higher฀relative฀risk฀for฀laryngeal฀cancer฀ [222] . It฀has฀been฀suggested฀that฀the฀mechanisms฀underlying฀carcinogenesis฀are฀mediated฀by฀ acetaldehyde฀formed฀by฀alcohol฀and฀cigarette฀smoke,฀a฀process฀that฀is฀also฀encouraged฀by฀ microbial฀oxidation฀of฀ethanol฀by฀the฀oral฀microlora฀ [223] .฀The฀implications฀are฀especially฀